I could see wi-fi (even if I don't believe it) but how would this compete with BLE/NFC/Bluetooth? It's not like I want my wireless earbuds or my apple pay to go up to the internet and then back to device i'm using it from, right?

"Sidelinks will allow 5G-connected vehicles to communicate directly with one another, rather than going through a cell-tower intermediary."

I bet google wont implement that part... Just like they didnt implement ad-hoc wifi

Wifi direct is definitely implemented on android, not sure what you are specifically talking about?

Look at this thread: https://issuetracker.google.com/issues/36904180

Not unless you want to control your connectivity/data. Imagine how bad ads will be if you can't block them and they follow you around without mercy.