The community installation works with other apps, but you’ll have to install them through the command line because the UI won’t allow you to (it thinks you have a missing dependency). See my original post. I don’t know if the same can be said about the “native” Knots installation. Umbrel is planning to fully support it as a drop-in replacement for Core in the future though.
Btw, if you’re on UmbrelOS v1.x, you’ll have to use different command than the one shown here, this one only works for v0.x. See this this thread for some v1.x commands for managing apps from the command line.