It is going to be hard for small and poor countries to make BTC a legal tender, in these countries people are more worried about what they are going to eat, rather than using a censorship resistant currency. Take note that even in El Salvador, a greater population of the people do not even use BTC, neither do they even really understand how it really works.
I think implementing a certain thing to be a legal tender relies solely on the government and its financial institution. Implementing BTC as legal tender is not that hard if the government and its financial institution wanted to just like how El Salvador accept BTC as legal tender. The only challenge is the pressure from outside force and the process of establishing the foundation of the said financial system in maintaining the effectivity of its implementation just like what happened in CAR.
Any country as long as the government is willing can accept Bitcoin as legal transaction, after all it is the government that sets rules and policies over its jurisdiction.
Not every country can follow the example of El Salvador, there are other structures and very difficult things such a big decision is usually only decided by single person. So if it has to be decided democratically, then I dont think it will happen.
It is because not every country shares the same belief as the leader of El Salvador. Just like in my country, even though Bitcoin is legal, it is only recognized as a mode of payment and not as a legal tender.
Someone has to have the courage and take full responsibility and enforce it, just like Nayib Bukele. In Europe, I think it is extremely difficult for it to happen. But one thing I am almost certain of is that EL Salvador will not be the only country in the next few years to accept Bitcoin as a legal method of payment.
Legal tender and legal mode of payment is two different thing, aside from El Salvador, many country also recognize Bitcon as legal mode of payment. Here is the list of countries that accept Bitcoin as legal mode of payment:
https://b2binpay.com/en/countries-which-allow-cryptocurrency-as-legal-payment-method/