I got my I-140 approved from company A. Right now working with company B. My PERM is submitted with company B, but not yet approved.
Can I switch to another company C now and start PERM with company C? Would it affect my priority data since I haven’t reached I-140 stage with company B(current employer)?
Yes.
No. You can carry forward your PD with any new I-140 petition.
Fact is once you have been approved for I 140 it allows you to extended your H1B visa beyond 6 years. In case new company hires you after 180 days of I 140 approval, you dont have to apply any more I 140 and you are allowed to extended your H1B visa with any other company as long as you file on time.