Just so everyone avoids unnecessary grief, I can confirm that the Intel Wireless-AC 9260 Wi-Fi card is utterly
incompatible with Ryzen. The 8265 and 8260 both work flawlessly in my AB350, though.
UPDATE: I guess another user and I complained enough on the Intel forums for their engineering team to take notice. Mere days after I posted,
Intel just released a new driver literally yesterday (20.40.0, on March 20th), and it fixed the BSOD and disconnection issues. I verified this with both swapping out the cards as well as doing another clean install of Windows 10 with the 9260 installed. I'll run a two-hour YouTube video test and if that plays alright, I think this is good as gold.