In the same way they can(not) do it on Pixel phones - and I would be surprised if Google was not already cooperating with the state actors. You do what you can. Even open source drivers (which are not gonna happen when operating within tightly regulated radio bands) won't help if there's a hardware backdoor.
Ah nice so leave the phones in another room
Easy but for missing Step 1 of “Colocate with friends and business partners”