Frankly, doing business within EU from EU is more complicated than selling overseas, at least with certain digital products. VAT on digital services is a fantastically dreadful thing: you have to pay VAT to the country of your customer rather than your country. VAT MOSS [1] makes things a bit easier, but it still involves complex reporting and bookkeeping. When I was actively working on my startup in Finland, in the early days of this new VAT rule it was such a mess...
1. https://europa.eu/youreurope/business/taxation/vat/vat-digit...