I don't think it will be airdropped to wallets as alt airdrops happen. It will probably be given to wallets where a confirmed citizen of El Salvador is validated and thinking of using BTC in his/her future transactions. This will be a good motivation for normal people to start using crypto in day-to-day life and also use it as a regular currency.
I think that's the only valuable thing to do but it will probably take a lot of time. Hopefully, the free bitcoin does serve it's purpose and hopefully what you said that it will motivate them would happen. I envy them but at the same time I am happy, envious because that can't happen in my country and happy because if it doesn't happen then that means that crypto won't be taxed.