Using my phone as a key

[deonb]

One could tuck the key away so it wasn't easily found in the frunk. Just like those magnetic boxes that go under a car. It's always going to be a security concern short of the OP actually carrying the keys with them.

You can also put it in one of these in your Frunk - even if someone get access to the Frunk, they can't do anything with it:

The Run Lock - Home

(obviously take the battery out).