PlexAmp is an amazing bit of software for a phone. It doesn’t translate well to the desktop, but it’s still pretty good.
Your flacs will play lossless on wifi, and transcode to 128kbps opus on mobile. You can tweak those settings too.
Most smart TVs have a native plex app available too.
Setting up fail2ban to block people trying to brute force the admin panel is a good start.