For the vendor (non-)consent thing - Consent-O-Matic provides an appropriate framework.

(Whether such a side would even care about the preference/consent is another matter entirely - I'd suggest a throwaway browser identity and cookie auto delete for a start, anyway.)

Creating rules has a bit of a learning curve the first three or seven times, but I find that more interesting to do than go through a hostile/dark pattern cookie dialog or such the third time.

Hm, maybe the appropriate functionality from CoM could be re-wrapped as a TamperMonkey module...

Web automation for the masses 😱