H1B extension with Perm not approved, but PD current

[Engineer1234]

I joined Company A  in May 2019 and they were quite slow in getting the Perm. My Perm was filed by Company A  and is currently in process. My PD is April 2011, and I have been on H1B since 2006

My H1B at Company A  expires in April  2022, and they were planning to file the extension around Oct / Nov (180 days in advance). However, today my lawyer said that since my PD is current, they cannot file H1B extension under AC-21 and the only option is to wait for AOS. But that is a problem because just in case the Perm does not get approved till April and then in that case if Premium is not available (for H1B ) I am stuck . Also, somewhere this seems to be leading to a gap scenario where I might need to move to H4 and I am not keen on doing it. Any thoughts on this?

The other thing is - that I am also close to getting an offer from another company B. This raised one more question in my mind. If I get an offer from company B , can they file for an H1B given that my PD is current in both Eb2 and Eb3 ?

Both company A and company B are well-reputed product companies