I think there is no such Option in LOS yet. GrapheneOS on the other Hand has this Option for years. If you want to safe at least your signal messages/contacts Molly has a similar function to encrypt after a setted time of not using it.

If its only cuz of the unlocked bootloader have a look at DivestOS, Graphene or Calyx

Edit: i use my ING Banking App on my Pixel 6 with graphene and before on my OP6 with Divest