Yes but in this case it's something that parses stuff received from internet, not a calculator or a sudoku app. There's a tiny chance that a specially crafted email could be exploited. It's very unlikely that it would be explicitly targeted as it's a niche app that now gets less than a download a day, but still IMHO it's dangerous.

On the fdroid community I once recommended to everyone a 100% offline app that generated generic images for contacts without pictures and because it was abandoned in 2018 I was downvoted by many who would say "what if an attacker with some top tier social engineering skill persuaded you to use a specially crafted exploited image as a contact picture on your phone, then when you used this app to parse existing picture, the 6 years old image library would be exploited and your phone hacked??" - something that has the same probability of "what if the same day you found on the ground a winning lottery ticket a meteorite hits the ground, bounces back all the stairs and hits you while waiting the subway pushing you on an incoming train?"