In Japan “recycle shops” are ubiquitous. There’s a chain called “Off House” that will buy just about anything, and also operates branches that specialize in used books, electronics, outdoor goods, etc. There’s another chain called “2nd Street” with a few branches nearby. They’ll appraise your items on the spot - usually takes 15 minutes or so during which I’ll browse the store - and pay cash. They typically buy for about 50% of what they intend to sell for, which is quite fair IMO.
I can think of about 10 locations off the top of my head in my city, and there are probably more than that. I never throw away things that are in a usable condition - better to get a little money back and it feels better knowing someone else might use it. I’ve also bought quite a bit of 2nd hand stuff - bikes and skis for the kids, clothing, etc.
When living in the US I used to make use of a local consignment shop. Pawn shops are also pretty ubiquitous, although I never actually tried selling anything there. And there’s always Goodwill and Salvation Army if you just want to conveniently get rid of stuff and avoid waste. Goodwill (and other charities as well, I assume) can write you a donation receipt that you can use to claim a tax deduction (although I never bothered).