I'm not finding any place where people share their keymap config (if that's the right way to refer to how you've configured which key has which actions bound to it), so here goes mine - and I hope to have feedback and to be inspired by yours, as well!
From some awesome inspiration, I updated the setup :-) thanks!
I moved the layer switcher to the left hand, and moved backspace to my thumb, so I don't strain my pinky so much.

I moved the arrows to right under my right hand... and added a button to make the switch to this gamer layer permanent. So basically, to go from layer 0 to layer 1 permanently, hold left thumb button, tap right thumb button. Tap left thumb button to switch back to layer 0.

And I added a num pad, also right under my right hand, where I'd expect it.

original:
I just got my first mech keyboard with fewer keys than a 'regular' keyboard, and set it up this way:

with the TG(1) switching to layer 2 for gaming/some extra symbols:

and the home row is modded to GASC like in https://precondition.github.io/home-row-mods#how-to-use-home-row-mods with 160ms tapping term.
I am mostly struggling to get used to this way of typing and I still spend a lot of time on finding symbols, or correcting extra or missed keystrokes. But, I'll try to update this when I have more experience.
Critique away!
It does! For using so many different layers, don't you feel it's slower to change layers and back than to move your hand if you had a bigger keyboard? Or am I missing the point. I'm quite new to this.
Your layout is dazzling. How do you remember all of this... !
Nice! Initially I was definitely slower, but my choice (for the moonlander) was primarily for the ergonomics (the split keyboard really helps with my posture and back), and then I just started experimenting. My layers were intended to just get all of the features just somewhere, and then step by step evolved into the current setup. There's some logic to each layer though, and I mostly use the arrow keys (left hand pushes some button (no clue which, I'm typing this on my phone from the couch now and it's solely muscle memory) and my right hand is now as if I was on the arrow keys, with the pageup & pagedown keys nearby), in combination with the modifier keys that's 90% of my navigation while coding.
Apart from that there's the symbol layer, where the keys I use often are fine, but others I just spam keys until the special character I'm looking for appears and then delete the rest lol.
The mousenav layer is mostly a joke, but has saved me once when my mouse broke so worth it!
If you have any other questions, shoot!
Oh, that's a nifty way to think about it, modify with one hand and map it to a situation as if the other hand was where you'd have it, e.g. with the arrow keys!
Have you tried home row mods? In theory, it sounds good...
What do you mean by home row mods? Layer switching happens on my home row, when holding those keys, if that's what you mean.
Ah yes, that's what I meant, but putting heavily used modifiers like shift, Ctrl, alt under those fingers and mirroring the setup between left and right hand, trying to make the most out of those 8 keys where you don't need to move your fingers for.
Ooh, interesting, I guess the layer modifiers are kind of the same thing indeed. I have too many layers for that so I don't think I'll fit that in, but I like the idea.
Ok, you inspired me :)
I moved the layer switcher to the left hand, and moved backspace to my thumb, so I don't strain my pinky so much.
I moved the arrows to right under my right hand...
And I added a num pad, also right under my right hand, where I'd expect it.
EDIT: updated the screenshots
I've also moved backspace, delete, and enter to my thumbs, way better :D
I don't know about having the same button do multiple layers, especially tapping is not my thing (because then I don't really have control over going back, unless that's again a tap of another key, which feels like overhead), I just hold a finger for a layer on my other hand, and release when done.
That said, you do you and it could definitely work, experiment with the most wonky setups and keep what works!
Wayyyy better :-D
And I see! Yeah I've definitely already jammed keys realizing I'm on the wrong layer, but I need a permanent switch to the gaming one. But I'll try the switch on hold til release with an extra a hold to switch for just the gaming layer, I like that idea more. Good one!
Oh yeah my gaming layer is indeed one I "permanently" enable, by going to the layer switching layer, then choosing the one for the gaming layer. I don't use that layer for anything else but it's good to have
Oh yeahhhh...I updated the screenshots, now I have a button in layer 1 to make the change to layer 1 permanent. the options are endless!
I think you pasted the wrong screenshot for the numpad by the way