Start by learning docker, you don’t have to selfhost anything yet, just learn to run a container, specially to run automated stuff. Then learn to build the images and run docker compose.
Also you could start checking any form or infrastructure as code. I usually hear about ansible and nixos.
This helps having a way to redeploy your services in any hardware easily.
I don’t think there are services like that, since usually this means deploying and destructing an instance, which takes a few minutes (if you just turn off the instance you still get billed).
Probably the best option would be to have a snapshot, which costs way less than the actual instance, and create from it each day or so yo run on the images since it was last destroyed.
This is kind of what I do with my media collection, I process it on my main machine with a GPU, and then just serve it from a low-power one with Jellyfin.