Hosting your own services. Preferably at home and on low-power or shared hardware.
Also check out:
I mean good that you are interested in hosting a proxy, but Nginx Proxy Manager hides away a lot of features and is probably not such a good idea to use when you want to run more complex and security relevant apps like a Signal proxy.
I know this is a bit annoying as an answer, but learning a bit of regular Nginx is probably the better idea in the long run as you usually outgrow NPM quickly.
Not annoying at all. That's exactly what I meant by "opportunity to learn more". I guess then I could fire up a container with nginx instead. Is there a way for me to transfer all the settings from NPM to the new container?
The config files should be in the volume you mounted in your NPM container. Probably /data/cong.d/. You can either edit them like normal nginx configuration files (NPM just runs normal nginx in the background), or you can copy them to a standard nginx instance.