Phone lock screen mfa with passkey and/or security key?

Questions
1

Hi everyone I apologise if this is a noob question but I can’t find an answer online, is there a way to use multi factor authentication with the lock screen password on your phone? If you have a high threat model and live in a country such as the UK, you can be compelled to give the authorities your password and failing to do so is a criminal offence and can be punishable with jail time (UK RIPA part 3, section 49 https://www.legislation.gov.uk/ukpga/2000/23/section/49)

However in part 9 of this law it explains that:

(9) A notice under this section shall not require the disclosure of any key which -
(a) is intended to be used for the purpose only of generating electronic signatures.

So my reading of this is that if mfa was enabled with a security key or and/or passkey, then you could comply with a request and hand over your password but not have to hand over your secuity key and/or passkey, because such things are exempt under part 9. Meaning you could comply and avoid prosecution while knowing that the password you are handing over is essentially useless if they dont have the ability to get past the mfa. Or would tools like Cellebrite have enough info with your password to be able to bypass the mfa anyway?

Does anyone know if this is possible please and if not can it be explained why or provide links where I can read up on why so I can keep learning please?

Thank you

2

This is a very specific question about a specific thing. I would ask a professional tech policy or privacy lawyer and not trust anyone else providing info on this.

3

They are clearly not exempt since they are being used for authentication, not generating electronic signatures, so your premise is flawed. Regardless, what you are describing is not supported in any modern operating system.