I ended up having a similar issue with Mint, where I couldn't get the PC to wake up after it slept/locked from being idle. Found the solution here: https://forums.linuxmint.com/viewtopic.php?p=2103191#p2103191

Appears to be an issue with Nvidia graphics cards. You need an extra command in one of the default files.

That's fixed my issue. I assume it was also the culprit for Pop!_Os.