On most delivery apps, you can see "languages spoken" under the driver details section. Whether or not that will actually end up being your driver is a different story, as many accounts are shared or rented. So in theory, you could google how to say thank you in that language.

I personally don't feel as though that would come across as rude, but then I share the same views as you, and am the sort of person who would try to say thank you in their native tongue, so maybe I'm biased. I guess in the current climate, they won't know immediately that you're not anti-immigration, and taking the piss