A reference to your post but I might have misinterpreted what you wrote. That is, the speed you quote may have referred to just the built-in card reader or it may have referred to the chip (USB2642) as a whole. I took your comment as referring to the chip as a whole.
But I just pulled the datasheet and I think I did misinterpret what you wrote. From the datasheet:
The flash media interface can support sustained transfer rates exceeding 35 MB/s.
and
The flash media interface can support sustained transfer rates exceeding 35 MB/s if the media and host support those rates.
It’s still true that we will need Librem 5 v2 in order to get full value out of either 4G or 5G.
Maybe someone can give some actual speedtest results with either the BM818 or the modem of this topic, as connected via this chip (and with WiFi killed to be sure that data is going via the cellular modem) showing faster than 35 MB/s (280 Mbit/s). Of course, the limiting factor can be anywhere in the path, not just this one chip - and that includes factors external to the phone such as congestion on the user’s tower and/or congestion on the backhaul and/or the user’s data plan.
The BM818 only claims “150 Mbit/s” (download) so we would probably have to lower the bar for that modem and just ask that anyone can get an actual speedtest result close to that figure with that modem.