https://docker-curriculum.com/
Best resource I found so far. I tried docker’s tutorial but it was not good at all.

I would never handle email myself. I would instead use a provider, turn off all filters and set up a mail server locally that works via the provider.
That way I don’t have to convince my ISP to set up a PTR for me, handle DMARC or SPF. Or care if my IP is blacklisted.

It does look fishy.

How about running the OS from a USB stick? Put all images you want on it and mount NAS drives at boot.

I want to but COSMIC DE.