If we want to turn altcoin to cash, will we need to sell it for BTC first, and then send the BTC to service for conversion to USD/EURO before finally to bank?
If your altcoin doesn't have trading pair to the stable coin and it's much better to convert them all to the bitcoin (low volatility) and then convert them all into the your local currency or if you are using the crypto payment app just like crypterium and you can also convert or send your bitcoin your local bank account and that app will be converting your amount instantly or you can try to use the service that already made by binance too just like bank transfer.
I hope you can get the best way to liquidate your money to your bank.