what's the easiest way for customers to leave us a google review?

timing matters as much as the link. ask right after the job's done, while they're happy, and send it by text or whatsapp so it's one tap. asking a week later gets a fraction of the reviews. two don'ts: no discounts or freebies in return for reviews, that's against google's rules. and don't hand customers a tablet in the shop to review on, lots of reviews from one device tend to get filtered.

Yes. Open your Business Profile (search your business name while logged in to the owner account) and look for the ask for reviews / get more reviews option. It gives you a short link that opens the star-rating box directly. For older customers I'd turn that link into a QR code and print it on the receipt or a little counter card. Pointing a phone camera at something is easier for them than typing anything.