For the very basics of KiCAD, their own intro is helpful. I had to wrap my head around the workflow: first schematic, then PCB.

Once you grasp that, some keyboard specific stuff is described by Joe Scotto in this video. He tends to rush his tutorials though, so best to go through the KiCad page first or revisit the video after.

For resources, I found Ai03's library of footprints to be perfect, except that his vertical 2U were not oriented how I needed them, which I realized too late, LOL. Then, the kbplacer plugin by adamws was absolutely invaluable and saved me so much time. I used JLCPCB, because even when US-China tariffs were at their worst (and goodness knows they could be again if Trump gets a hangnail or something), JLC was still the cheapest option for me.

If you've never done a PCB before, I might humbly suggest keeping to a fixed layout for the first go-round. I did that on my first board and it worked perfectly for what I intended it to be. I got a little ambitious with this one, and ambition+inexperience+impatience led to a flawed project.