I just checked Trezor documentation and their state:

At the moment, we are in the process of setting up a new strategy for implementing new coins into Trezor. Please, be patient, our team will not be accepting any requests to add new cryptocurrencies until the process is finalized. Once this has been done, we will inform you through our public channels.

So potentially, in the future, we might develop an app for trezor too. Shouldn't be that hard ;)