Feature: Sim mode at runtime #6832

Job	Run time
1/4	13m 54s
2/4	13m 6s
3/4	12m 20s
4/4	11m 5s
py-3-latest	19m 44s
flaky	6m 18s
_remote_background_indep_poll	5m 12s
_remote_background_indep_tcp	6m 47s
macos 1/5	18m 1s
macos 2/5	23m 33s
codecov	5s
	2h 10m 5s

Provide feedback