Self hosting on an Android mobile?

Hey y'all, I was reading this self hosting user survey at selfh.st and noticed that some people said they self-host on a mobile phone.

I have an Android phone here I could use and I can picture setting up the phone and then just leaving it plugged in, in a corner somewhere. That seems like a good use for all that computing power but I'm not sure how to get started.

I found this article showing how we can use a phone for a web server:

https://www.digitalocean.com/community/tutorials/host-a-web-server-on-android

But is there any way to host other apps / services on a phone? Does it have to be rooted first?

Any pitfalls or other tips you can share when to doing this?

Thanks!