we are planning to migrate around 500 projects, 12000 users, 250 custom fields, 100 screens, 30 workflow from On-Prem (Datacenter Instance) Ver. 8.22.3 to Cloud.
Can we do a one short approach to move all in one go or do we recommend to go in staggered approach (set by set).
Without actually being involved in your migration it's hard to provide specific recommendations. That being said, in theory, nothing should prevent you from moving the whole instance at once.
Assuming you've tested the process thoroughly, a single migration is often easier on users as you cut them over all at once.