Something that hasn’t been discussed here just occurred to me to ask if radio communications protocols via IoT devices can be done in a safe way as an alternative to the second/burner phone.
My feelings are this protocol is quite limited by the bandwidth to ensure perfectly secure communications but there is the really nice tradeoff of not having to have a second phone with all the temptations of doing bad security and privacy practices, also they are quite cheap and disposable.
That said, it’s heavily reliant on a lot of plain text protocols and requires the user to do a lot of your own privacy management manually.