Polyglot v2 on RPI 5?

Spent all day setting it up including getting the legacy Isylink up and running (because I need CAI and the PG2's DSC plugin doesn't have the features I need that are in Isylink's node server).

So then comes installing PG2 and I get errors like this:

Reading package lists...
E: Package 'mongodb-server' has no installation candidate
E: Unable to locate package python2.7-dev
E: Couldn't find any package by glob 'python2.7-dev'
E: Couldn't find any package by regex 'python2.7-dev'
E: Package 'python-pip' has no installation candidate

E: Package 'mongodb-server' has no installation candidate

And then I find a post in this forum that says you have to install the lagacy raspian lite which won't work with other stuff I've already installed.

So what do I do? Just keep running PG2 on my old RPI3 and don't shut if off? Can I run it in a docker container on the the RPI5 even though PG2 itself dockerizes for each node server?

Edited June 27Jun 27 by sorka