Advice on entering help desk field?

I'm worked for 20 years in legal admin. But during my life I've accumulated a lot of computer and Office expertise (Windows, Mac, bash, zsh, etc.), and usually can grok the ins and outs of new software pretty quickly.

In addition to my existing knowledge I'm a good problem-solver and know how to Google answers and adapt them to the problem at hand, and already have done a lot of informal help desk at every job I've been at. The help desk at my current employer know I'm a good liaison.

I get a kick out of helping people with their problems one-on-one.

In short I feel I'm a talented amateur who has the above inclinations and the skills, but I'm at a total loss as to how to take that and transition it to a paying job opening in the field.

Do I need formal certifications, and if so, from which entities (I see Microsoft and Google both have certificates)?

Are there ways to discover where the gaps in my knowledge lay (which I probably don't know exist) for a typical help desk technician?

Is there a way to learn what an average help desk tech salary in my metropolitan area would be?

This and any other advice would be appreciated.