Those are all very different levels of difficulty IMO:
Linux is almost trivially easy, only slightly harder than the usual configure && make and has very few dependencies.
Firefox is pretty painful but it's doable with a decent amount of care and bandwidth.
Chromium is a fairly typical google project where the recommended first step to building it is to become a google employee but some alternative workarounds are also available if that's not practical.
Linux is almost trivially easy, only slightly harder than the usual configure && make and has very few dependencies.
Firefox is pretty painful but it's doable with a decent amount of care and bandwidth.
Chromium is a fairly typical google project where the recommended first step to building it is to become a google employee but some alternative workarounds are also available if that's not practical.