If you're using an exchange I don't think a vpn is needed. Because in every country where crypto exchanges are used, no VPN is required, they can easily trade without VPN. However, I have seen many times that there are some exchanges which are not open due to network problems but can be accessed very easily if VPN is enabled. But to my knowledge there are no crypto exchanges that require a vpn to access. You can trade any exchange without VPN if there is no VPN required to access the exchanges in every country.