zlacker

SSH in and you have access to basically everything. The stock setup has two partitions for the OS (it toggles between them when you update, or toggles back if it fails to boot a few times) so you can:

Dual boot (disable updates and install any two you like): https://remarkable.guide/tech/dualboot.html

Some lower level details here: https://github.com/ddvk/remarkable-hacks/issues/304

And installing a specific release is largely automated: https://github.com/ddvk/remarkable-update

Last time I did it, I just did it manually - back up the OS version you want over ssh, then restore it whenever you want (on the non-active partition). And screwed it up the first time, and had to do a recovery: https://github.com/ddvk/remarkable2-recovery (requires using the contact pads on the spine for USB access - not too hard to solder up a pogo pin thing, but might take some time to get the parts).

So I'd recommend the automated way, though I haven't tried it yet :)

There's a (single) relatively active discord server if you want specific Q&As with other people too, or to double check whatever the current recommendations are (probably do that, as I'm somewhat out of date): https://discord.com/invite/nQ6nHwfDfc

And do definitely back up your data partition before making any major version movements tho, in case something doesn't work right and you need to roll back. I forget if/when that's necessary, but it's a good safety net just in case. And <8GB isn't much to store just in case.