Unlikely to yield any results but I'm running out of options.
My personal email account was linked to my company phone for a short time while switching personal phones.
Unfortunately, I never switched it back and have since left the company - loosing access to the phone and its number.
Which is now causing issues with 2FA.
Is there a way to get my old company eSim back?
Standard company IT process is to fully reset phones when staff leave.
If your Google account (assuming that is what you are talking about) was on the device when you handed it in, it shouldn’t be any more.
What you are asking doesn’t fully make sense as you can access Google accounts online if you know the password and delete devices from within, then add new ones including for 2FA. Is the problem really that you have forgotten the password?
If so just abandon the account and start a new one - the old one gets deleted after a period unused.
Obviously you cannot get an eSIM reissued to you when it belonged to a company - huge security issues should be obvious.