Just a follow-up on Discord after using it a few days. It seems to be working pretty well. I ended up switching from the stand-alone Discord software to the browser version (using Edge since I don't really use it otherwise). The software worked fine, but it kept my monitors from going to sleep. I don't have this issue with the browser version.
Setup is a private Discord server running on Microsoft Edge on the PC the scanner is connected via 3.5mm cable to an $8 Sabrent USB microphone/speaker adapter (the server can be set up from the Discord site and does not need any port forwarding and/or firewall changes).
The scanner PC joined to a voice chat channel on the Discord server setting the microphone and speaker settings to the correct devices and using VOX, so it only transmits when the scanner breaks squelch.
Using a second Discord account to listen to the channel on my PC using a browser or iOS app (a login can only join the chat once...if you want to listen on the phone and PC at the same time, you'd need separate accounts).
Optional: I'm using "Scanner Recorder" program by Dave Jacobs that I've been using for 20+ years to record the scanner 24/7. It only records when the scanner breaks squelch.
Is it as good or better setup than Zello legacy? Not really, but it's a pretty simple, quick and free way to just listen to the scanner stream that can be set up in a few minutes. If you are doing something more fancy like controlling the radios, that's beyond this.