[outime]

If staying in Europe is a requirement, NL or UK usually pays much better than France (given that you're already an inmigrant and some companies may pay you less than a native unfortunately). Otherwise and as many others have suggested, US is the answer.

[kaybe]

I wouldn't think about moving to UK right now, since the rules may change any day.

[bestouff]

If staying in Europe is a requirement, obviously UK isn't a valid choice.

[mcv]

The UK may be leaving the EU, but it's still in Europe.

But I agree, it's not a good choice right now. Let the situation settle down there first.

[mcv]

NL is in my experience not great for employee developers. Somehow companies tend to believe managers should make more money than programmers.

For freelancers it's pretty good, though. Biggest boost to my income ever.

[fargo]

How should one go about finding freelancing opportunities in NL?

[mcv]

Recruiters. Many of them may be scum and parasites, but they also seem to be an essential part of the ecosystem. Make sure they know how to find you.

LinkedIn works quite well for me. Keep your CV up to date there, make sure it's clear that you're freelance and looking for work, and they'll find you. At least that's my experience. You can take a more active approach than that if you want, but this is working well enough for me.