You can control the mpd stream remotely via malp: https://gitlab.com/gateship-one/malp
If you can connect to your home network via VPN you could also try to play from the remote music library via Samba share. This will not give you offline playback support though, which most Subsonic compatible clients support.
I never used it but if you’re willing to pay for Symfonium you can directly connect it to a Samba share. Or WebDAV, if you’re running Nextcloud anyways. This will give you offline caching as well. Don’t have any personal experience, but sounds convenient. Wish there was a FOSS music player with such a broad cloud storage support. Not having to run a dedicated music streaming service sounds great.
OP didn’t say if they’re on Android but RadioDroid is an amazing internet radio client. The original version doesn’t get updated anymore, but there’s a maintained fork. You’ll have to install it via Obtainium or directly download the APK: https://github.com/morckx/RadioDroid/releases