IMO the best split would be:

- All Google consumer devices and products (Pixel, Chrome, Android, Nest)

- Search

- Ads

- YouTube

Search, Ads and YouTube could all survive and prosper on their own and then the Google devices company can pursue a similar strategy to Apple, have devices pay for software.

How could search survive without ads? Charge users per search?

Search could still serve ads. It would just have to integrate with Google Ads in the same way a non-Google user would.

Sell ads to the highest bidder which could be the other entity or someone else.