I've a Good news for you then you can achieve that for free. Since 2018 I've only seen ads only a handful of times and even that was because I was watching TV with my family on my sibling's "smart TV".
My setup, unlockorigins on web browser and next DNS on phone, also instead of YouTube use newpipe or even better tubular (tubular is just a fork of newpipe with sponsor block) and I pirate all the movies and TV shows.
What I don't understand is why LMG kept quite about this. No matter how much PayPal paid them it wouldn't be more than how much they would be making with affiliate links also why join hands with karma which is also doing same and stealing from them.
The general rule of thumb is, if a single PR changes lots of things then it won't be accepted.
I'd suggest breaking it into multiple PRs and possibly reaching out to someone on the core team to explain what you were trying to do and how you've done it kinda like RFC. Ideally this would've be done before you started with a major change but still.
I see you also mentioned original devs are no longer active. In that case you can send PRs but don't expect them to get merged but instead if you are still using it, try to update and fix other things as you see fit and people will see it and start using your repo and if at any time original devs comeback maybe they can official handover project to you or accept all your PRs. And this is totally OK as long as you are not breaking any license original devs had, that's what forks are for. If you want you can rename and do rebranding but that is not necessary unless original devs had trademarked the logs and stuff and that original repo is completely dead.