I wish there is everything for Linux.

fsearch has the looks but last time I tried I needs to wait for it to scan, no background indexing.

You can bet stocks like SpaceX will sky rocket in price, since people know there are aliens on other planet now, not just conspiracy or theory.

I have seem similar thread on Reddit, this answer I liked the most.

Hello can you hear me? Oh wait, wrong planet, sorry

Is the gist of it.

Also using PurelyMail, tt’s the cheapest non-free email service I can find.

It passes email delivery tests, setup SPF, DKIM and DMARC easily without issue.

The downside is that it’s basically one man handling whole this service, but I assume this service has been fully automated because the margin of profit is so low.

some sort of dashboard with monitoring and statuses of all my services

See if Uptime Kuma suits your needs.

Are there any major no-no things a newbie might do with Docker/selfhosting that I should avoid?

Allow password based SSH authentication, you should look into key based authentication

I wanted to have it behind a domain, how would I achieve it?

Use a reverse proxy (like caddy) which serves different content based on domain name.