There have been open-source smartphone builds.

I'm going to try to do a better one over Christmas break. I'm going to annoy poor nostr:nprofile1qqsqxefne258ydmfgm2wfl02fsdqgs0d5wx29kweg9amxcqxew4t7kqpzamhxue69uhhyetvv9ujuurjd9kkzmpwdejhgtcppemhxue69uhkummn9ekx7mp0qy2hwumn8ghj7mn0wd68ytn00p68ytnyv4mz7tjlpwg into giving me tips on optimising it, too :D