At first the game would crash on me on launch, so I downloaded a configuration file from PCGamingWiki to get the game running.

And while the game launches now after setting the renderer to d3d11, I can't get past the title screen. No matter what keys I press, nothing happens. Only thing I can do is open the console, but that's about it. For what it's worth, my space and enter keys do work for skipping the intro titles.

What could possibly be the problem?

I managed to get it fixed.

Turns out that, after installing the cfg file from PCGamingWiki the game could boot just fine, but apparently it was reading a newly created configuration from C:\Users\My_User\Saved Games\Nightdive Studios\DOOM 64

And while I had seen that address in numerous other online posts that had similar issues with launching the game, the problem for me was that I couldn't find that Saved Games folder. Unsurprisingly (in hindsight) it was because my system language is not in English, so I kept looking for a "Saved Games" folder with no luck.

Pasting that very same .cfg file from PCGW into that folder solved my issues.