After years of using Feeder on my phone and some other random stuff on my laptop, I switched to FreshRSS on my server and the big thing is everything stays synced. My read and stared articles are all where they should be. I run fluent reader on all my devices and tailscale keeps me always connected to my reader so I can save articles on my phone when I don’t have time to read them then read them when I get home on my laptop or tablet.
I use a GPU but that’s only because my CPU is a first gen ryzen with no graphics. I highly recommend any recent Intel CPU that supports quick sync. You’ll have an easier time and pull way less power. i7 might even be a bit much honestly I’d look at i3’s or even celerons. They’re easily capable of what you want but you can always get something better just for future use.
If you go the android route turn on Apps Only Mode in the settings. It gets rid of the home screen ads for the most part and disabled a lot of the “features” that Google tries to push.
Casting is always weird with networking like that. I’d highly recommend trying to find a way to run jellyfin locally cause nothing will really make Tailscale play nice with casting in my experience.
I’ll say that I’ve run both Kavita and Calibre+Calibre-Web. I’ve stuck with running Calibreand Calibre Web together. Kavita was great but since I read on kindle and Kavita-email never worked for me I went back to Calibre. I also prefer calibre since it lets me convert files and change the cover images.
Personally I had more issues getting kavita to work the way I wanted than I did with calibre.
I’ve had similar issues with TrueNAS over the years. My solution was always to just remake the container but that is a hassle. I did that probably 3 or 4 times while I used TrueNAS which eventually led to me switching to a standard Ubuntu server install.