Looking into the process a bit, it seems like something you could theoretically do with any BIOS for the same card model. You need to either use an older version of NVFlash or override any safety features in newer versions to cross-flash BIOSes. Outside of doing something wrong in the flashing process, the biggest problem seems to be with making sure the power limit of the BIOS you're flashing over doesn't go far past the power limit of your card. Since the Zotac GTX 1650 LP card doesn't use a 6-/8-pin connector to the PSU, going past 75 W is a big no-no. Of course, cross-flashing in general is usually a horrible idea, but there are valid use cases for it. Like here with this card's less-than-ideal thermal profile.
But now I don't know how to figure out what the fan/temperature profiles are for a given card. Those aren't listed on the TechPowerUp database. I don't really feel like cross-flashing 5 different theoretically-compatible BIOSes (
[1],
[2],
[3],
[4],
[5]) to find one that works the best out of what's currently available. And I really don't want to flash more than once to minimize the chances of something going wrong.
Neither is the BIOS for this card, for that matter. So I decided to upload the BIOS to the site myself. Hopefully it shows up there soon enough! It's important to have these things available for preservation's sake. It'll also help for anyone who bricks their card and (for whatever reason) doesn't have a backup of the BIOS available.