There are a lot of people saying gain of function but it doesn't really mean anything. It's like one of those feminist slogans that says "LOVE IS LOVE".
No one just does gain of function research in the same way no one just does cooking. You cook something so what was the laboratory cooking? What was the order for?
This is in the public domain: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4797993/
However this is a hell of a read so I'm going to explain in simple terms what the actual research project was: To create SARS-2.
The scientists were being paid to create SARS-2 in a manner as if it emerged normally.
They were being paid to make another SARS virus with the same origins as the first SARS.
This paper is a progress report saying that they were half way through.
The average person might struggle but I can read this and so can Fauci. That's what this document says. It's reporting the scientists progress on cooking up a SARS-2 virus and proving that they've successfully completed the first half. They made SARS 1.5 I guess.
Note that when I say half it's somewhat approximate but not far off. It's common in research projects to do the first half or a portion first representing a major milestone and proof of concept before continuing on with the rest.
COVID-19 is actually a SARS-2. Its media and medical name is COVID-19. Its scientific name is SARS-2. From SARS-CoV to SARS-CoV-1 and SARS-CoV-2 specifically.
Most people miss it because it's in an attachment but early in the emails Fauci sends this paper to his high level internal staff to find out if they are tied to it no doubt for purposes of liability.
SARS-CoV-2 is exactly that same as what they were paying scientists to create and they were half way through in 2015.
We always need to think very carefully about the terms we use to refer to things because it can sometimes be misleading. It's far worse when you know what the terms COVID-19 and GOF really refer to in this case.
TLDR, one of the first emails Fauci sends in a panic summoning an emergency meeting with high level internal staff has an attachment and the file name matches a 2015 progress report from Hubei & North Carolina stating that they are half way done creating SARS-2.