I'm not 100% certian that there is a recommended way to do what you are trying to do. Work object ID generation is central to the way that case handling works and this sounds like what you're looking for is a fairly radical departure from OOTB. There are probably custom/non-guardrails ways to do it, but it's likely involved and may be a case where scoping a project with PegaConsulting is the best way to go about doing that.
Start with your case-details tab of your rule-application, and specify a distinguishable prefix there for your work id's.
Then run pega tracer when you create some work and search for your distinguishable prefix in the tracer details.
That will allow you to find the relevant activity and data transform rules that generate your work-id's. See which of those activity or data transform rules are non-final ones, or are extension rules. Those would be the ones you would enhance to get the results you want. /Eric