Powering the fan from gpio pins probably isn’t going to work out well either, they are 3.3v and 5v. Powering the fan from the PSU is going to be similar to powering a pi off it, I believe you should step the voltage down to what each needs, where the fan is 24v I think the pi is 5v. Your PSU is probably 115 or 220 v. For connectors I would expect to have to redo them yourself with micro fit, molex, jst or w/e you want and can get. On some of mine I just did single pin molex on the pins of the white female connector for fan headers, it doesn’t lock but it works if you don’t have a lot of movement. This page is awesome for connectors info https://www.mattmillman.com/info/crimpconnectors/common-jst-connector-types/