Prop up a phone so it can see the port LEDs of the switch and do a video call to that phone.

Then run around the house and plugin a laptop at each socket and see which port lights up.

If you have a pi there, why not just just zero tier to that pi and monitor it’s zero tier IP? You can do a very basic keep alive check with any monitoring system that can ping and then alert trough whatever script that monitoring system can call.

Or just have an old android phone running macrodoid and keeping that connected to usb power all the time.

If phone is no longer connected to power, send a text, call a number, write an email etc. You will need a sim card though. But one with very limited data can be had for very little money.

You need routing from one vlan to the other on your firewall.

Why not build it with container lab running Arista vEOS or cEOS switches? You will need about 2GB of ram per container.

Try Arista EOS. You can download docker (cEOS) and virtual machine images (vEOS) for free once you create a free account.

You can also spin those up pretty easily with containerlab. And automate/manage them with ansible.

Backups are more important than raid levels.

Have automated backups that comply with the 3-2-1 rule first, you can migrate raid levels later.