Bitcoin has not failed in El Salvador, there are some people using it.
What is highly needed is to educate the people, people in El Salvador confuse the Chivo Wallet with Bitcoin.

This that work in El Salvador in regards Bitcoin:
The ATM machines use standard Bitcoin QR codes and work with any Bitcoin Wallet, max daily limit $1000 USD in multiples of $20.

What does not work, the Chivo Wallet personal and the Point of Sale:
The point of Sale when I was in El Salvador in Nov 2021 it was completely broken, Bitcoin payments would vanish, it would only work reliably for the Chivo wallet at the time.
This made payments at major stores like Walmart not possible with a non Chivo Wallet.

The Chivo personal wallet, it works but has serious design flaws, for example Bitcoin in El Salvador is used mostly for small transactions as such you would expect the Bitcoin lightning to be the QR code by default, but no it is the hardest one to access furthest away in the menu, the default QR code is the one provided by Chivo which is only readable by Chivo Wallets, standard Bitcoin and Bitcoin Lightning wallets can not read the QR code from a Chivo Wallet as such you need to request another QR code which only very small bussiness are willing to do. From my experience the personal Chivo Wallet does work in Bitcoin and Lightning mode but it is not a QR code provided by default which causes a lot problems like not being able to pay in places like Walmart.

The point of sale had many catastrophic bugs which hopefully they have been fixed by now.

The good thing of the Chivo wallet is that its QR codes are easy to recognize just by looking at them, at the center if there is a $ sign it is a Chivo code, a yellow B a Bitcoin QR code, a yellow lightning then it is a lightning QR code. So as a tourist as soon as I saw the $ in the QR code I knew it would not work and requested a lightning or Bitcoin QR code which sometimes they were not willing to provide and the transaction could not take place. My experience was that few places would generate the proper QR code and that was because they were willing to learn, the lightning QR code was kind on hidden in the menu which is a terrible design.

My recommendation to the people of El Salvador, is to modify Chivo to provide a standard Bitcoin lightning QR code by default not hidden far away in the menu that way tourists can use Bitcoin to make Bitcoin purchases.

The people that created the ATMs did a fairly good job, I only found one issue with the ATMs but overall once you know how they work they are very reliable. The only issue I found with them is when selling Bitcoin you need to let the ATM know you are done paying it is not automatic, otherwise a timer kicks in and resets the ATM without a warning causing you to lose the funds (you get the funds back by opening a case but it is a lengthy process).