Where can I search for remote entry level positions once I am Google Ads certified?

While you can use the "usual" online job sites, you may also want to offer your services to someone within your inner circle of contacts. 

For example, do you have any friends or family members running their own businesses?

I got started by helping local business owners. My route was to run the ads for a couple of friends for free. At that point of my career, I cared way more about getting a few case studies under my belt than an immediate payoff. Those friends and family members knew I was a complete beginner, but were happy to let me run small campaigns with the idea I'd be at least somewhat competent and be a good steward of their budget.

Things blossomed from there!