I own a handy asus x00p with android 8 that fits my hand (released in 2018). I have a newer android 11 device (released in 2020) but it’s larger and heavier and I don’t really like using it.
What are the security risks, if I go ahead using the 2018 model to 2fauthenticate?
I’m gonna have to ask you to elaborate:
how can I keep it offline? I need to keep the device online to receive the code, right?
2fa codes are usually time based. As long as the system time on the device is correct it should be able to generate a matching code
OP never said how they got the codes. Could be SMS.