I went with the supernote Manta and I love it. It is Android based, not Linux, and the ecosystem is really sparse. But you can easily side load F-Droid or the aurora store and that opens everything up. I have next cloud syncing my documents and moon reader giving me access to my calibre library.
It is first and foremost a note taker and drawing pad, sacrificing lights and color for writing feel. The writing feel is amazing though. No subscriptions, non replaceable pens, support for replaceable tip 3rd party pens.
It’s cost is quite a bit more than remarkable 2 or the pinenote though.
I don’t have immich but nextcloud is no problem. You just add a field to each user in authentik and it maps to the existing user.