Great points, as someone who is very happy with their current home automation and services, checking in the config files to a git repo was the critical step. Also backup volumes since many containers tend to store state in some binary or internal DB. At the very least try restoring the config to verify you have what’s needed. The containers should start even if they have no media on it.
In terms of tinkering not being fun anymore. That’s okay, sometimes you need a break.
A point that is sometimes not brought up enough in my opinion is to plan for loses. What can you afford to lose if you can’t backup everything (due to price, etc.)? config files and photos or personal data are relatively small (compared to something like a media library) and should be prioritized.
Knulli works well.
The version I installed did not have support for the hinge, although I believe newer versions do offer that now.
BT headphones are not supported from what I recall. I have not yet tried external BT controllers or HDMI out.