I think exchange with a complete stranger in fiat every time is also leave a trace, it's really risky if someone want to hide Bitcoin transaction from the government.
Unless you're doing it with an undercover officer or you're always doing it in the same place with cameras all around and you start drawing attention from either bank employees or security guards it's probably the safest thing. Really hard for somebody to even start tracing you and on what grounds at all.
The hard part is trying to hide your wealth cause if you buy a 50k car while unemployed, then all your secret dealings were a joke.
The best way the @OP need to wait until his country unban Bitcoin, move to other country which accept Bitcoin or he can convert his BTC to stable coin using Bisq if he's want to trade Bitcoin. If he's want to cash out his Bitcoin to fiat in other country, he shouldn't use his bank account or anything that link his real identity, he should use digital wallet which only require phone number verification on that's country.
He's not doing any of that, he accepted bitcoin for his business and now he stopped!
There is no solution for him, moving out of the country means losing his customers, and decentralized exchanges are of no help when you plan on accepting the currency as they don't protect you at all, there is simply no chance of him avoiding this the moment the authorities will enforce a complete ban and do punish lawbreakers. Again, this is only for the scenario where
they actually care and enforce such a ban, but then all that is needed for him to get busted is a police officer coming into his shop asking him if he accepts bitcoin and there he has it, the moment he says yes it's game over!