I think it’s good in that it gives Librem 5 users more options, and maybe the option to roam outside their home countries more cheaply.
There are many eSIM providers out there: some are from regular mobile carriers (T-mobile, Vodafone, etc.) and/or MVNOs (resellers on those carriers’ networks), and some are from purveyors of “travel solutions,” e.g. Airalo, eSIM2Fly, eTravelSIM, just to name a few that an internet search turns up. They all have their own privacy policy, I’m sure.
It’s the user’s call whether to subscribe, and to which one(s), based on the particular privacy policy, the company behind the product, the country it comes from, etc.
And since in this case it sounds like the eSIMs would be loaded onto a removable card (like this commercial product: https://esim.me/ ), the L5’s killswitch should still be able to disconnect it when the user wants.
The carrier whose network you’re on will always have the ability to know who and where you are, and potentially the various eSIM providers as well. So choose well.
Personally, I’m not concerned about hiding from the network carrier; I need them for service, and they need to identify my SIM card. I’m also not very concerned about “The Government™” or law enforcement agencies… unless I’m traveling in a “hostile” country, which I don’t see myself doing.
That said, I still prefer regular old physical SIMs, even while roaming abroad. It’s just so easy to swap them around, and they provide calling and SMS/MMS, while eSIMs do not.