I have to check but that could be a problem.
pop_os is based on Ubuntu, and Ubuntu 18.04 is the highest for Treasure of Nadia.
The funny thing is this error is often related to Chrome.
I am afraid Treasure of Nadia will not run under Pop!_os 20.04.
I have to investigate why it is not running in Ubuntu > 18.04. It might run in Pop!_os 18.04 though.
Edit:
Suddenly I thought do you have the ffmpeg-codecs installed?
in Ubuntu 19.10 It is:
sudo apt install ubuntu-restricted-extras
not sure what it is in Pop!_OS 20.04, I have yet to check this jewel of Debian install.