Every "split" mechanical keyboard currently being sold that I know of

split_keyboards.md

• Kinesis Freestyle (Terrible key switches. Mushy and un-lovable)

• Kinesis Freestyle Edge (Traditional layout with too many keys, mech switches, proably too big to be tented easily/properly)

• Matias Ergo Pro (Looks pretty great. Have not tried.)

• ErgoDox Kit (Currently, my everyday keyboard. Can buy pre-assembled on eBay.)

• ErgoDox EZ (Prolly the best option for most people.)

• Diverge 3 (Looks great. Might buy one. Ergo-dox really has too many thumb keys anyway. This might be a better design.)

• Diverge TM 2 (Cool idea. Magnets! Too few keys for me.)

• Keyboardio (Halves can optionally be separated. Looks promising, but too few keys)

• Dygma Raise (Nice thumb keys layout, but no arrow keys and probably too big/unweildy for effective tenting)

• UltraErgo (Does not appear to be mechanical)

• Ultimate Hacking Keyboard (Small layout, mech switches, intersting-looking thumb attachments but missing arrow keys! And Kinda ungly)

• Lets Split (Dunno what this is yet)

• Mistel Barocco (no arrow keys, but looks good if you like 60% keyboards)

• Goldtouch (Technically one-piece, but close enough. I've used these. They're crap.)

• Goldtouch Go (Technically one-piece, but close enough. These are also crap.)

• Comfort Keyboard Split Magic Keyboard (This looks terrible)

• SafeType Keyboard (Also looks terrible)

• Axios (Something gloriously weird that is under development. Maybe.)

• Cheap Split PCB Boards for sale (Totally DIY. Soldering required!)

UHK now comes with a 75% layout, including arrow keys and more thumb buttons and a row of F keys with wireless option.

Keychron Q11 split is another option.

Naya Create is another interesting option.

A few links stopped working.