As someone who lived in Russia for a while, I have personal experience with these mini-exchanges. They're the Internet equivalent of those currency exchange stands at airports, I wouldn't call them full crypto exchanges like Binance.

They're a pretty interesting phenomenon. Some do KYC, some don't. Some are fully automatic and just need to be "topped up" occasionally, some are fully manual. They usually provide an easy on/offramp to/from crypto, but they usually have high fees and minimum transaction requirements on top of an unfavorable exchange rate. Sites like bestchange exist to aggregate all the different rates and slice a cut from the affiliate revenue.

It's nice to see how they work (or don't) from the legal side. In my mind they've always existed in a grey legal area, since some mini-exchanges openly proclaim their registration in e.g. the UK and some just don't say where they're headquartered.

They do work, but they've always felt a bit shady, and I've felt anxious using their services. Centralized exchanges are way better in regards to support and have a better exchange rate to boot.