Tonga with a population of around 105k won't really compare much to El Salvador with a population over 6 million. How many people in Tonga even have access to the internet and are interested in Bitcoin? I don't see a huge impact.
Mexico doesn't seem to be anywhere near making Bitcoin legal tender:
"We are not going to change in that aspect. We think that we must maintain orthodoxy in the management of finances [and] not try to innovate much in financial management," the president said in response to reporters’ questions about Bitcoin.
source: https://decrypt.co/83472/mexico-bitcoin-legal-tender-president
Tonga has an Internet penetration of about 41%, although it's also reported to have 72.5% of it's population in social media. Not very trustworthy number I reckon.
source: https://datareportal.com/reports/digital-2021-tonga
Well, add to that the fact that Tonga only have a total population of about 105,697 people in (2020) ...so based on your active Social media statistics about 31 000 people will probably not use Bitcoin.
If about 60% of the people does not have access to the internet, then the statistics are even worst... (About 42 000 people will have Internet and they will be able to use Bitcoin as legal tender)