We rarely see electrocapacitive keyboards, not to mention EC splits. Well, Sviatoslav Bulbakha aka ssbb_me just assembled the very first prototype of Tako, a 34-key EC split sporting an STM32 chip.
This particular build features DES Carrot 35g domes, DES housings, DES sliders and DES #7 silencing rings.
It's the first prototype I made, and it works as expected. However, it's a 4-layer PCBA-only board, so it can be quite expensive if you only want a single keyboard. Currently, I am working on a DIY version using STeMCell and hopefully nice!nano with hand-solderable components (SOIC and 0805). Support for nice!view is also planned – ssbb.
If split EC boards are your style, check out sekigon's Corne EC build, and also Cipulot's [https://github.com/Cipulot/CorneECRevival|CorneECRevival]].
And if you need an introduction to electrostatic capacitive (EC) non-contact switches and keyboards, Cipulot mentions the basics in the EC87 post, and he also wrote about his EC projects in the calendar: 2022 Roundup: the year of EC.)