ok i figured out how to do it

1. i needed my expired Biometric Residence Permit. one part of gov.uk says it can be 18 months expired, the other (correct) part says it can be up to 24 months expired. i don't think they understand what the word "expired" means but i'm thankful for it
2. i had to use the gov.uk app. the app does not work on phones without google play services. it also does not work on grapheneos (which does have play services).

i fucking hate this