They (just him?) did a whole load of SFF / 1 Litre reviews a while ago - it's probably better (easier) to watch his youtube channel as then you actually get to see what he's talking about.
He also covers some of those "brandnames" and addresses some differences when they ordered identical devices and compared what was received.
Depending on what your future plans are, some of the newer boxes are multi-NIC multi-Gb devices so you might find something "better" there.
It seems you need more USB ports than the Green / Yellow support... and USB hubs aren't great... so, unless you're purchasing the hardware to support the foundation, then other options are better.
As many others have said, getting a SSD for the Pi is probably best - if your hardware has enough RAM. No hardware is wasted, small cost, etc. IIRC, you'll need to take a full backup (all options enabled), do a full clean re-install and then restore your backup. Then select the option to move your data.
The benefit of going to another device (ie passively cooled N1xx) is that tje storage and memory allow you to expand what you're doing with HA - more addons, better graphs (ie Grafana), longer term history, etc. If you're not interested in all that, stick with the Pi.
Most bare-metal installed apps are in /etc/ or ~/.config/... maybe under /opt/ or /usr/ - just copying those files out on a regular basis is usually good enough.
Might be a little more tricky if you're trying to backup a database / live files, but those apps usually have some documentation about backups.
If it's a container or flatpak, etc. then it's probably somewhere obscure.
I keep my data backups (docs, photos, etc) separate from the OS backups.
So, depending on what you're using to do the backup, often they can just simulate a restore and just check the backup's not corrupted. Not really a restore, but at least you know it's not trash.
If you've backed up your data with a simple copy / sync (ie not a "backup" program), then you can restore your data somewhere else (maybe even jist a part of it) and do a compare.
But, yeah, if you're restoring the OS, then it might be ok restoring it in a VM to check it...
I'm slowly moving towards no OS backups and using Ansible to be able to recreate the system(s) from scratch... of course I need to backup the ansible files too 😉
You will break something - and that's good, it's the best way to learn - but you'll want to make a note of what you did / went wrong / how you fixed it.
Future you will still break things and be grateful that you wrote that thing down
You'll buy something and find next year it was the wrong thing (too small, too large, too old, too new), so just get second hand stuff until you know what you need.
Cabled networks are so much better than wireless, but then you'll need switches and cables and shelves and stuff... so using today's wifi is fine, but know where you're heading.
You need to store you stuff - that'll be in a NAS
You need something to run services on - that'll be your server
These might be the same physical metal lump (your 2nd laptop?), they might be separate... play around, break something and work out what feels right for you... and then put your data on there
... and that'll break too.
Just be aware... if sync files between devices. That's not a backup. (Consider you've deleted / corrupted something - it's now replicated everywhere)
Having a NAS with 10 drives in a RAID6 array, is not a backup. It's just really robust against a drive failure, but a deleted file is still a deleted file.
Take a full copy of your data off your system - then restore it somewhere else.
Are you trying to solve one problem, but then find the next?
If you solve the problem of the media selection (which looks like some form of database replication), then what happens if both parents select media they don't have at the same / similar time - you've stated elsewhere that this is the bottleneck.
I think it's going to be much simpler to just replicate the media and let them work locally.
I don't know what your script with rsync is doing, but syncthing can limit bandwidth and have exclusion patterns, so perhaps one set of parents don't want anything from GenreA and you could exclude that.
Similarly if both parents lile GenreC and you don't, then just sync that between their systems and save your storage.
Security is the output of removing vulnerabilities and insecure configs
So, the real answer is: what's the minimal software you need and the most regularly updated.
So, my choice is Arch.
Yep, installation takes a little longer and needs more technical skills, but only install the bits you need (also learn a little more this way) and then updates are tiny and can be done as often as you're comfortable with.
Whatever you choose, it will break / die / be deleted or corrupted one day, so always backup your data separately than the OS (separate drive partitions can help) and you're done.
This is probably the main point - not buying a new phone when the manufacturers release a new model.
I would add though that Fairphone are also improving the entire industry by not using cheap labour, paying fair wages and not using conflict materials, so there is more to this than just eWaste
But, I agree don't scrap existing phones just to buy another - even if it is Fairphone
Here you go (serious answer 🙂):
https://support.fairphone.com/hc/en-us/articles/17121765976849-Shipping-Costs#shipping_countries
Read the bit at the bottom of that page if you're not in the main table