Yes, OP was asking about chocs.

And another thing: All of the keyboards that were recommended to you here use QMK (or KMK or ZMK) firmwares and thus are equally configurable.

You’re welcome. Full disclosure: I did have some troubles with the keyboard, as one of the USB-ports was wonky, but I was an early adopter and they sent me a replacement left half. They are a little hard to reach at times, and seem to concentrate on selling custom keycaps now, but aside from building a keyboard yourself, I doubt you will get one as cheaply as that.

If you want to contact them, they have a discord server (called momoka), maybe you can try there?

(I had to take a look at the keymap to verify, as I have been using a custom keymap for years.)
Yes, to switch to the second layer, you press and hold one of the FN keys and to switch to the third layer, you press the shift key in addition to that.
They do have a VIA-enabled firmware, in which you can change which keys are used for that in a graphical interface and, if you familiarize yourself with QMK and how to build it yourself (not as hard, as it may sound), you can have a keymap with as many layers as will fit in the keyboards memory and can have all kinds of useful functions.
My keymap for the Momoka has five layers, a key that will activate one layer when tapped and another when held, Home Row Mods (The keys on the home row produce letters when tapped and Shift, Ctrl, Alt and Win/Super when held), etc., etc.

The model I got (early adopter) had an aluminum top and bottom plate. I guess it still has those. I just stuck some rubber feet under it and placed the halves on two hardshell glasses cases that had the right height ;) , but you should be able to fix something more permanent to the bottom plate with screws or magnets (glued to the plate).

https://www.momoka.co/ergo for US$ 180,-?

Agree. I made the big mistake to switch from a full sized, but split (Microsoft Sculpt) keyboard on the German standard QWERTZ layout to a fully split ortholinear with 36 keys in Mine-Layout, with Home-Row-Mods pretty much in one go and without taking enough time per day to really train (on AgileFingers or Keybr.com). It took me more than a year to get back to barely acceptable typing speeds but I always had the feeling to be worse off if I would go back and start over.

My advise would be to change only a few things at a time and get comfortable before changing the next thing, but since you are already trying out Miryoku, I can only wish for your success (others have done a switch as big as the one I did without any problems), and to have fun with it.