You don’t have to imagine. The starlink constellation is a working and profitable massive deployment of orbital compute. (It doesn’t use rad hardened hardware as far as I can tell)

Starlink is impressive but calling it compute is a stretch.

It's not that far off from a residential router with a bigger antenna.

Starlink satellites have such a low orbit that they experience non-negligible atmospheric drag, which is why they have to be replaced at such a rapid rate. All proposals for orbital datacenters propose placing them in sun-synchronous orbits for maximum solar exposure, which puts them right at the edge of the Van Allen Belt at best, meaning they'd be exposed to dramatically more radiation than a Starlink satellite.