There are roughly a million violent crimes a year. It is not credible there are 3x as many defensive uses of firearms that are somehow being missed.
The page you reference indexes a few thousand over several years. Seems likely an undercount as the page claims but not by that much by probably a couple orders of magnitude.
Your first link shows 2400 documented cases since 2019 which is more than I’d have expected. But clicking through those examples… many honestly don’t seem that sympathetic. Stuff like “shootout between X and Y, but Y shot second so it was self defense”. Or “X fatally shot Y with no witnesses to contradict his self defense claim”.
The page you reference indexes a few thousand over several years. Seems likely an undercount as the page claims but not by that much by probably a couple orders of magnitude.