Google reviews

I have an e-commerce site that I have had for close to 20 years and can't find how
someone can post a google review. It does not have a physical address. What am I
doing wrong. Never really wrong. Never paid attention to SEO in the pasty. My mistake.

Will building up google reviews mitigate the damage of poor Trustpilot reviews

Definitely you can add a google listing for your e-commerce and do it without an address. Phone verify or email verify. What i see is that most of e-comm sites are mostly reviewed on sitejabber, trustpilot, resellerratings instead Google My Business listing.

'20 years ' without any company calling the owner!? He asks a blackhat forum for advice?

Mate - unreal.

You can use your home address and have it hidden. If you want G reviews, you must have a GMB listing.