I modded my GPU to have an 80mm RGB fan, so I have a little experience in this kind of thing.

So, you have this one here, but there's a few others on Amazon too.

https://www.amazon.com/SilverStone-Technology-Silverstone-FM84-Controller/dp/B01KAYOWJU/ref=sr_1_6?crid=2WRUFWGY2XN81&keywords=80mm+white+fan&qid=1651181663&s=electronics&sprefix=80mm+white+fan%2Celectronics%2C94&sr=1-6

You'll have to remove the fan from the housing, cutting all of it off aside from the fan and hub. You then see what type of mount the fan/GPU uses, and 3D print one up. Something along the lines of this, but there are a few different types, so make sure it's the correct kind:

https://www.thingiverse.com/thing:4506608

Then you just glue the fan to the proper type of mount and screw it in, and you're pretty much good to go. You can deal with the fan PWM cable either by running it out of the back of the GPU, or you can get an adapter cable to plug it in to the fan micro connector inside the GPU shroud.

Something like this, but double check the mini fan connector to make sure:

https://www.moddiy.com/products/4-Pin-PWM-Fan-Connector-Male-to-4-Pin-Mini-GPU-Fan-Connector-Female.html