And the obvious answer is…
Yes
The one I was talking about was basically unbranded (generic), and all the reviews say that it simply doesn’t work and the price was very “good” - so, yes, I care what the reviews of that card say.
You can say that about basically all IT technology. Does that make it a ripoff when it is first introduced? It’s complicated.
One way of looking at it is to look at (for storage) price per GB (say) and ask what premium you are paying for the higher capacity card.
For sure, if you don’t want to spend that much and you don’t need that much storage then don’t.
It is likely that whatever “affordable” card you bought today for $X, you will be able to upgrade to a card with twice the capacity in the foreseeable future for another $X.
512 GB card arrived: check
file system set up: check
music collection synced to it: check
Now, what am I missing? 
In case it comes up, I was reminded once again of the annoyances / delights (you choose) of ext4lazyinit.
This will particularly be a problem with people initialising larger cards. (Cards will arrive with an exfat file system, which almost certainly is not what anyone would want. So setting up the file system is the first thing that you will have to do.)
The symptoms of ext4lazyinit (which is the default) are that the file system creation will complete almost immediately … and then a system process called ext4lazyinit will grind away for eternity actually initializing the inode table, the light on the card reader (if you have a light) will flash away interminably, and you have no progress indicator, no way of knowing how long until it finishes, … and these cards are not fast.
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- - KIOXIA EXCERIA HIGH ENDURANCE (BiCS FLASH™) Max. Write Speed(s):
– 32G µSDHC ≤ 30 MB/s (similar to my current Samsung PRO Endurance card)
– 64G/128G µSDXC ≤ 65 MB/s
– 256G µSDXC ≤ 85 MB/s
- - KIOXIA EXCERIA PLUS Max. Write Speed(s):
– 32G µSDHC, 64G/128G µSDXC ≤ 65 MB/s
– 256G/512G µSDXC ≤ 85 MB/s
Yesterday I compared above microSD cards and asked myself why would be to recommend above two (within this thread)? But rather I’d like to rethink here why, or actually just go ahead and buy (preferably 
) ordinary (simple) microSD card like KIOXIA EXCERIA with following (deducted) feature:
Is it support for CPRM an important consideration (before buying an high-capacity µSD card) for all of our potential (personal) usage (if not public media content related) within a Linux phone? Is it KIOXIA EXCERIA indeed the one to recommend for non-CPRM content on Librem 5, non-CPRM private data requirement(s) friendly (up to someone’s own preference), as GNU site describes here (related to DRM, of course)?
Besides, I beleive that Micron i300 microSDXC cards (128GB to 1TB) are non-CPRM too (with CSD related value of 000b), yet another ones under SD specs version 6.10.
Well, sorry if bothering, but lollypop users probably like to stick, ensure they are using CPRM enabled microSD cards, just like here:
P.S. Feel free to link this post of mine somewhere else if here not 100% adequate, if anything needs to be added (perhaps, without investing into, sort of mandatory, CPRM security support) by admitting that I have no non-CPRM usage experience (and therefore asking for some quality opinion of yours).
CPRM must be an anti-feature.
What command do I use to find out whether my uSD card does or does not support CPRM?
All of my content is audio and none of it is subject to DRM - so, support or no support for CPRM, everything should (and so far does) work.
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Yes, just recently, since March 2018, “our” authorities made CPRM feature optional (avoidable) with SD specification version 6.10. Non-CPRM µSD cards are, I guess (probably), just cheaper variants of technically very same, but encrypted counterpart. Link to another CPRM awareness reading (.pdf file): “How CPRM Works” is here: www.4centity.com/document.aspx?doc=4aae4d66-a727-449c-8675-119343c624a0
This question was some kind of challenge for me, so up to my understanding below one should work:
apt search mmc-utils
cd /sys/class/mmc_host/mmc0/
ls -l
- - look for exact mmc0:XXXX folder name
sudo mmc scr read /sys/class/mmc_host/mmc0/mmc0:XXXX
type: ‘SD’
version: SD 3.0x
bus widths: 4bit, 1bit,
Where version: SD 3.0x relates to SD Security Specification Ver.3.00 Compliant (CPRM Based).
Please change :XXXX as required. Same output was for 8GB and 32GB microSD cards I’ve tested, pointing out they are SDXC. SDHC should output version: SD 2.0x (will check another time).
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Only gives:
type: ‘MMC’
I do have a uSD card inserted (permanently). Do you have your phone yet? or you are testing this on a regular computer?
There is also ‘mmc1’ but that gives:
Unknown type: ‘SDIO’
Update: I tested that command on a regular computer that has a built-in SD card reader and it worked the way it did for you. Hypothesis: The uSD card reader on the Librem 5 is accessed indirectly via USB and so some shell commands that may purport to interact directly with an SD device won’t work or aren’t even usable. The mmc0 referenced above is the internal eMMC drive, not the uSD drive!
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It was proofed on PinePhone with Mobian on it (and on regular laptop with SD slot). Command is looking for scr file inside mmcX:YYYY folder.
Thanks for Update!
EDIT: @irvinewade, I don’t see this but Librem 5 path with scr file (by looking inside file manager) might exist inside mmc2 folder (meaning boot order is not the same as within the PinePhone)? And mmc1 on Librem 5 should point to USB Type C port (probably).
Yes, the uSD card reader uses a USB 2.0 bus connected to the Microchip USB2642, according to page 19 of the schematics.
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