You need a custom recovery to flash the ROM.
The 1440x1440 square screen is excellent for reading and spreadsheets but requires some apps to be "forced" into compatibility due to the unusual aspect ratio. The Installation Barrier The BlackBerry Passport has a permanently locked bootloader Blackberry Passport Lineage Os
Closing note If you want, I can search for any existing Passport LineageOS ports and summarize their status for your exact model—tell me your Passport model number (e.g., STL100‑1) and I’ll look. You need a custom recovery to flash the ROM