There's a browser extension called "Your Codecs." which can prevent YouTube from serving you AV1-encoded videos.

I wish there were more M.2 cards beyond just SSDs and wireless NICs. The idea of a small form factor PICe interface is underutilized and things like hardware codec accelerators can keep laptops with older processors usable with new standards for longer. It's sad how PCMCIA had an entire ecosystem of expansion cards yet we somehow decided that the much higher bandwidth M.2 is only for storage and networking. Hell, do what sound cards in the 90s/00s did and have M.2 SSDs specifically designed for upgrading older laptops that also have built in accelerators for the latest media standards. Hardware acceleration is energy efficient and can probably just be bundled into the flash controller like they're bundled into the processor, and unless you have a top of the line SSD you're probably not saturating the M.2 interface anyway.