Gain of function experiments are not all the same. If you use an artificial selection approach (wherein selective pressure is applied to a huge library of random variations), then maybe.

If you have labs picking-and-choosing what mutations to make (what usually happens), then no. That's just hubris. People stumble around in the dark, occasionally find a truffle, and pat themselves on the back for having such a great truffle-finding method.

Even for good artificial selection systems, mutational space is so gigantic that it's hard to cover properly: not just the point mutations (i.e. converting one amino acid to another) but also insertions, deletions and transpositions. There's no artificial selection system I'm aware of that can recapitulate mutational space.