Paths to becoming an Excel Expert

Dear community

I am a retired accountant, and have used Excel for many years, including
power user, macro and VBA development.

I would like to specialise in this field + maybe delivering Excel training,
maybe offering my services as a freelance.

What is the best path to develop this expertise? Is there a worthwhile
Microsoft Certification route - which I find confusing? And finally is it
worth sticking with VBA which seems to be on the back burner now?

Thanks for any suggestions.