but can other small countries follow in El Salvador's footsteps and what are the country's challenges in this regard?
There is no restriction for most countries if they wanna do what El Salvador did. Is it a challenge or a commitment?
Whatever it is, they're all free to follow it or they can work on their own terms depending on the capacity of their budgeting for purchasing BTC.
Small or big countries, as long as they're able to buy it and it's not illegal on them, they're free to do it.