In Heidi's hosted cloud, isolated per tenant, encrypted at rest. Region options including EU hosting are handled per customer; tell us your residency requirement and it is part of setup, not a fight.
Each company's brain is its own isolated store, not rows in a shared pile with a tenant column doing all the work. Isolation is enforced at the infrastructure boundary.
Data residency requirements vary too much to answer generically, by industry, by country, by customer contracts, so it is a setup conversation. Bring the requirement; the architecture accommodates it.