If it does not exist, it is not a disadvantage compared to anywhere else. In a sense it's an advantage, as despite the barriers, the capital markets of two EU countries (especially if they use the Euro) are still a lot more integrated than if you'd pick two random non-EU countries. The disadvantages of being from a small EU country would apply the exact same way but even worse if you were from a small non-EU country.
Digital regulation is not a serious blocker, as any EU founder can tell you. Per above, neither are cross-country capital markets a disadvantage of the EU compared to the non-EU world. Then what is the disadvantage? Do Japanese startups have it any better? Korean? Kenyan? Serbian? Mexican? Taiwanese? Malaysian? Singaporean? Do those startups benefit from "less regulations" or from cross-country capital markets? Of course they don't, yet I've never seen a single person in my life mention those countries' regulations or lack of cross-country capital markets. Because they don't have an advantage in those areas, showing that the EU indeed doesn't actually cause any disadvantages in them.
Digital regulation is not a serious blocker, as any EU founder can tell you. Per above, neither are cross-country capital markets a disadvantage of the EU compared to the non-EU world. Then what is the disadvantage? Do Japanese startups have it any better? Korean? Kenyan? Serbian? Mexican? Taiwanese? Malaysian? Singaporean? Do those startups benefit from "less regulations" or from cross-country capital markets? Of course they don't, yet I've never seen a single person in my life mention those countries' regulations or lack of cross-country capital markets. Because they don't have an advantage in those areas, showing that the EU indeed doesn't actually cause any disadvantages in them.