I suppose it depends on why you are interested. You mention institutions, recruiters and certificates, so I suppose you're looking at it with an eye on a career. Not sure how important certification is as we are still in the early days really. Getting some experience and being able to demonstrate it could well be sufficient for employers.
Once you've covered the basics, it might be worth focusing your attention on Ethereum and learning Solidity so that you can build some smart contracts. This is one of the strongest use-cases in crypto, and I think smart contracts are likely to transform business as well as wider society. If you have a quick look at the EEA, the Enterprise Ethereum Alliance, you'll see some big companies are sniffing around Eth, Microsoft being a notable member:
https://entethalliance.org/members/One of your links was Coursera, I've used them before and they're okay, but in my experience a lot of it is 'type this', 'now type this' kind of stuff, so you may not learn as much as you would be just
doing.
That Udemy basics link you had might be worth a go, and if that's any good, they also have
this on Ethereum - it says 'currently 85% off', £14 UK rather than £95, but I'm not sure if they always have these offers.
