Assuming they don't get a revenue cut, pushing back on Microsoft can in principle be effective here.

Microsoft decides what happens here, and presumably today they just take it on trust that hardware makers know what software to install. New driver? Sure. McSpam installer? OK. Maybe they have a guideline saying "Don't ship unrelated garbage" but today it's not enforced because why would you do that?

If the Microsoft customers (particularly larger corporate customers) tell Microsoft they hate this that policy will get tightened or if there isn't a policy one is introduced, and outfits like LG get told if you do this again we're taking away your update privileges, 'cos our customers hated this. Because (as I said assuming MS don't get a taste) this is all downside for Microsoft.

Pushing back on LG will be less likely to work because you already bought their product, so at most you can insist you'll forgo LG next iteration and they know such pledges evaporate in practice usually. Whereas Microsoft has contract negotiations every day, somewhere a $$$ contract is being renegotiated next week and if "Yeah, these LG popups suck" comes up - even if it's not a corporate system but the VP's niece's video editing suite for her vlog that's strictly unrelated - that Microsoft sales droid reports this was an impediment and it's on the list of things that don't benefit Microsoft.