you can home tenants in a data center close to them, run a copy of your app in each region including the datastore. keep a central db for accounts, billing, etc but user content is easy enough to shard regionally.

taken to extreme, cloudflare durable objects & workers let you place data very close to a tenant automatically; but you lose total write throughput on top of sqlite.

But this is kind of meaningless unless the tenants themselves are in one geo. Take linear as an example, this strategy works as long as your company that uses linear is all colocated in one area. As soon as you have remote people it falls apart.