Card scheme is very strict industry. Merchant account companies like Stripe are always at risk when they allow someone to accept money through their gateway. So if you want to avoid your money blocked somewhere or your brother be chased by Canadian tax authorities you will need legit setup
Your brother will probably have to open a business that is like agency:
he is curating your professional work and taking some % of it as fee, pays taxes on it in Canada and sends you from his business bank account the remaining funds as your personal earnings.
If its against social platforms then these platforms can do anything in their power to make the owners of the company suffer and try to pierce the liability protection. Poor fella can end up losing his assets to compensate "damages" to these platforms.
For EU based clients (doesnt matter if legal entity or natural person) you have to pay VAT at the rate of the customer's country. If EU legal entity has VAT ID number then you don't need to charge VAT.
For automated tax calculations you can try using Paddle - Revenue Delivery Platform for SaaS...
Maybe because of multicurrency card which knows in which currency to process your payments avoiding exchange fees, lower fees for maintenance and decent bug-free mobile app that was not made by random indians? + the only bank in Cyprus offering merchant account