Sorry, no, misread, thought you were on Gemini.
PCLineageOSPorts is an org I run. We haven't got LineageOS working on Cosmo just yet, but I did have another go last night. I need to finish my CoDi daemon for Cosmo Android/other ROMs.
i think you're stuck for the moment, the ROM will need signature spoofing support, and you're using the ODM/OEM-built stock ROM...