If you want to do something like this, you should at least use a software that is (1) open source (2) popular/reviewed (3) trustworthy. The wallet you named (Tangem) may be* open source but it is neither popular enough to be reviewed or trustworthy to be used.

* I say maybe because they have a github repository but I didn't check it to see if it is one of those fake open-sources that have a lot of close source dependencies. But definitely is not safe due to lack of reviews.