^^^ +1 to this ^^^

I was always overwhelmed by it too but finally just clicked into the Hardware section of the wiki (circled by WestMIguy) and realized its way less complicated than I was building it up to be. Start here.

You just order the all-in one board from JLCPCB following their instructions (the "All-in-One Board versions and how to order" section). Its a good learning experience on custom PCB making.

Then add a few things (Teensy, F9P, IMU, Cytron) and then put it all together. (see "Other Pieces to Be Able To Assemble")

Or order a preassembled one from someone (like DIY Farm Tech iirc). I think you still add the F9P in his case. Also order a GPS antenna.

Then you also build a harness which they give you a nice list of Ali Express parts to buy. ("Ampseal Wiring Harness" section)

Then scroll to the other components section and read up on the wheel angle sensor + harness, and steering with motor sections. I went with a Land Rover suspension height sensor from ebay.

I believe once you've read those pages you'll have a good handle on the hardware needed and can order if you want to proceed. I'm currently waiting on mine in the mail but AliExpress is sloooow. I already have an RTK base station and tablet, so all this hardware came to ~$1000. Once I have assembled hardware in front of me I imagine the software part should be fairly straightforward.