As pointed out Bitek, you're being somewhat loosy-goosy in your definitions and becoming pedantic.
In order for "gain of function" or "manipulating them" research to result in SARS-CoV-2, you need a starting substrate, aka a backbone virus you plan to manipulate. What is this first virus that they manipulated? The closest known relatives to SARS-CoV-2 is
RatG13 and
BANAL-52. The nucleotide identity between either genome is 96.1-96.8%. If I only mentioned that value, it would seem they are highly similar, yes? But not in the world of virology. Coronaviruses contain large RNA genomes, so a difference of 3.2-3.9% is huge. To put this another way, out of the ~30,000 nucleotides of SARS-CoV-2, that is ~1,000 nucleotides that are different. How can you purposely or indirectly select 1,000 nucleotides to be different through "gain of function of research?" Please explain the steps, in a clear manner. Don't just handwave, but how could a 1,000 mutations be generated in a rapid timeframe? And if you can, you should publish your results in a top tier scientific journal because such a capacity would take immense number of years and financial backing.
Another way to think about this.
XBB1 lineage SARS-CoV-2 only recently emerged. How much do they differ from the original Wuhan strain? They are 99.7% similar, they only differ around ~50 nucleotides with some deletions in the genome. So in nearly 3 years of a pandemic, with a virus that has circulated among millions (maybe >1 billion?) of humans, that has been further selected for by vaccine escape, the virus has only gained about 50 mutations. How is a 1,000 mutations going to be generated?
When scientists talk about "gain of function" research, they do not mean engineering a virus with ~1,000 mutations and hope it works. Now, if there's some other unknown starting virus, please show us how it exists. Second, show us how it was manipulated or mutated through "gain of function" research. Your previous link does not qualify given the already incorrect/false claims about SARS-CoV-2 that I pointed out.
And think about this. If your goal is to purposely cause a pandemic, or to purposely engineer a more severe respiratory virus, why didn't this pandemic occur with a highly mutated strain of SARS-CoV-1 or MERS??? These viruses were discovered 10-20 years ago, with years of research to provide it with "gain of function." So why didn't that happen? Think critically about what you are arguing.