That's a good idea. Gift cards are effectively interest-free loans, so they give you a way to "loan money" to local businesses which can later be "paid back" by cashing in on the goods and services.
I don't know how well it'd work out for Uber/Lyft and "Uber for X", though.
Of course, following the loan analogy, there's a risk of default. If your local taqueria goes under before things return to normal, all of those burrito bucks you bought are effectively worthless.
If they go bankrupt, yes. If they simply decide to go out of business in advance of running out of money (e.g., the owner is like "I've been thinking of retiring and now is a pretty good excuse"), write the terms of it so there's some obligation to refund the card.
That said, there have been enough Patreons/GoFundMes for local businesses, so I think that people understand that going bankrupt despite best efforts is a risk and enough people are willing to pay anyway to try to keep their local coffee shop open.
Hopefully you aren't buying enough burrito bucks to put yourself underwater :P Yet, if everyone buys some, that could still be enough to keep the business from going underwater.
I don't know how well it'd work out for Uber/Lyft and "Uber for X", though.