It is impossible for an individual, barring a very niche case. And why waste labor provided by someone else? So far as I know, edge is base on, but not a fork of chromium. If that is microsoft’s approach, I can’t imagine anyone doing differently. Except for maybe a government “forking” by close sourcing a “fork”. (Which someone has definitely done). What’s going to come of that? The FSF suing the US department of defense? I’d support it, but good luck.