This is admittedly a lazy post where I show that I haven't done much research.
Whenever I start searching around online, I find tons of smaller companies selling ergo keyboards or parts for keyboards, but they are always very pricey and don't match the layout I want. I quickly give up since it can take long to search store-by-store online.
The keyboard of my dreams has:
All (104) the keys. This means arrow keys and as numpad. I like the layout of my current keyboard (below). I guess this is called a "full keyboard"?
Mechanical and with plenty of clackedy clack in the keys.
Has the "Y" key on the left side of the gap! This is my biggest sticking point. I have realized that I type the "Y" key with my left hand 99% of the time and I don't want to change.
I am also willing to investigate split design keyboards if the "Y" is on the left and a numpad can exist separately which I could put to the right of my mouse. But still I'd prefer that to be attached.
I don't care about RGB or lights or much else. Take it or leave it.
It requires quite a bit of skills and tools, although jlcpcb can solder on the components for you so you can focus on only designing if you wish.
I would use Kicad to make the schematic and pcb, and Fusion 360 for any 3d modeling. Fusion has a free non commercial version, you just have to find it. They kind of hide it on their main website.
I like phils lab on YouTube for pcb design stuff but he isn't exactly beginner friendly and mainly focuses on audio related things.