I basically just lost interest, Firebase does everything I need ultimately. But I'd still argue it's the easiest way to deploy a side project!
They say it's because it uses Docker Swarm, I don't know if that's true.
On thing that's cool (to me) is that I once borked an update of the CapRover admin and while I couldn't get into the dashboard all my projects kept humming along without a care in the world because they were all in their own docker containers. I thought that was pretty neat (all of CapRover runs inside of containers as well and seems to be independent of apps it manages/monitors.
We have an official (paid, one-time fee) web ui here: https://pro.dokku.com/ . It's under active development.
There are others (ledokku, wharf, bullet, etc.) that folks in the community have developed/maintained, though I cannot comment on them as I haven't used them for more than 5 minutes.