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

I should look into AWS as well. Currently using a refurbished Datto NAS, running debian with everything in docker. I also have a r710! But I don’t have room for it at the moment.

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.

I assume a lot of people interested in selfhosting also enjoy the hardware side of things, making it more prominent than VPS.

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