The dev said to play in fullscreen at a lower resolution as a workaround.. but that only works if you're using a "stretch to screen" scaling option in your monitor's config (or GPU driver)
That sounds like your GPU driver problem. Typical Nvidia and AMD drivers contain the option to preserve the aspect ratio when scaling. You should be able to play without any weird stretching, with black side bars.
Yeah, that is what I meant; stretch to aspect ratio. It doesn't matter if it's in GPU drivers or monitor settings, they all have it.
It's very ugly upscaling compared to something like the pixel perfect integer scalars. Nothing like how a CRT handled resolutions outside its 'native'. This is why I don't use it, and have it forced off in GPU drivers because certain games overrode my monitor setting (like Dungeon Keeper 2 from GoG). Scaling only working in fullscreen is another downside, I play most everything in borderless due to frequent alt+tabbing (and setting desktop to a lower res is a big no no).
Also, I seem to have figured out why the game (and certain others) wasn't scaling with those programs; it's actually a full doubling of the resolution without any in-betweens. So because I don't have a 16:9 4K display, even 1024x768 can't be scaled up, because the vertical resolution winds up 1,536, and my display is a max of 1440. I forced the game to 1280x720 and it worked, but was VERY cramped. So my hope that they would do multiplier scaling is ruined. 2x or nothing.
At this point I'd take the slightly blurry font upscaling over straining to read text. I can't even play the game when I have my contacts out (wear glasses in morning/night). Just wish the scaling option got backported and we all didn't have to wait a long time for the next major release since it's a
huge QoL feature to playability and doesn't affect the game content..