I haven't but I did built relatively large projects before (e.g. browsers) and basically it depends mostly on 2 things :

• are you in rush? If not just let it run over night, if you are then delegate it (if you can afford it and matches your threat model) to a cloud provider (rent a couple of instances for however long you need, that's where the hourly pricing matters)
• is the build system properly setup for reproducibility, e.g runs in a single container on AMD64? if so just start it and move on, otherwise be prepared for an indefinite amount of tinkering

I think it's interesting to do but honestly as someone else mentioned, builds are signed. In fact at the end of https://grapheneos.org/install/web#verified-boot-key-hash you get the verified boot hash. The goal is precisely to check that you actually get what you are supposed to have running. Basically the big picture of reproducible builds is that you do NOT have to do it and can STILL verify that you have exactly, up to a single bit, what should have.