Another update of LineageOS 16.0 (for SD835-Pro1 only) is available at
https://findus.zwergenschaenke.net/~puma/linux.html#lineagepro1.
The ROM dated 20230516 gives you backported security patches up to the 5 May 2023 ASB. No other changes since last month. As usual you can refer to the tarball of local mods to learn all about differences with respect to the official lineage-16.0 tree.
Have fun!
You can store batteries at around 30-40% battery and if they aren't connected to anything, they'll hold the charge and capacity.
If you want to use it for something, there are 5V to 4.2V converters, you'll get those on ebay for 3-5 dollars.