You can sync your Roll20 and Paizo accounts. Once you do, you’ll need to think about the order in which you buy things.
If you buy the Pathfinder Core Rulebook from Roll20, and your accounts are in sync, then that unlocks a free PDF copy on your Paizo account.
Alternatively, if you’ve bought the PDF from Paizo, and your accounts are in sync, then you’ll get a discount on the Roll20 purchase.
The Roll20 also provides a free character sheet with automatic rolls and stat calculations. The Character Art Pack has 230 tokens supporting the Core Rulebook.
The new Pathfinder Bestiary is also out, but not yet on Roll20. That’s a work in progress and should be available later this year.
Are you planning on buying Pathfinder 2e?