We don't support it at the moment. Adding fonts is on the roadmap, but, unfortunately, I cannot give an ETA for this. What fonts would you like to have, we may be able to add those to Termius?
I have been trying Termius on and off for a year (I subscribed), but still couldn't switch away from Blink due to lack of custom font support and inability to map Capslock to Ctrl (but I solved this by using HHKB with my iPad, which has Ctrl in Caps position)
Additionally, please, please consider adding traditional TOTP. I don't like Authy, because its initial authentication requires SMS, and the fact that Authy acts as middle-man between me and the service (e.g. to delete non-TOTP Authy token, the service need to call Authy API to disconnect the user before _I_ can remove the token from my phone)