Any tips on dealing with symbols for programming?

My preferred way is to have one symbol layer with all the symbols. It prevents having to constantly doing shift/unshift or switching layers (I personally call this "shift dancing") 😀

It looks like this:

https://keebogram.pages.dev/hypership/

On my 34-40 key layouts I put all the symbols typically used together in programming on the same layer, including symbols that usually require Shift, along with all the numbers. This makes it comfortable to type whole formulas without leaving the symbol layer and without needing Shift. Important bigrams that I can type without switching layers in the middle include <= >= != += -= = /= %= &= |= -> / / => := :) ;) . I also optimize the layer so that none of these are same-finger bigrams. Because = appears in so many bigrams, I found it convenient to map it on a thumb key.

I make sure all the mods are comfortable to use and in the same place on all my layers, either as bottom row mod-taps or on opposite side thumb keys or worst case as a oneshot mod. I don't need Shift on my symbol layer, so one less mod to worry about.

Probably my favourite feature for a programming key map is _ on a base layer thumb key. That makes typing snake_case_names a breeze.

As a programmer with a 36 key keyboard, I actually find symbol typing easier for the most part than it was before. Mainly because I find the number row symbols easier to touch type when there isn't any hand movement involved. Do you look at your hands when typing %? How about F6? I did it without even realize I was doing that, but now that I have a numpad layer for all my numbers and number row symbols (and no legends on my keycaps to prevent me from looking even if I wanted to) I touch type those symbols much better than I did before.

Your keyboard didn't have dedicated {} keys before either. Those were shift+[] before, and now, for my layout, they are symbol layer+{} which is the same number of keystrokes and same level of complexity, though I had to relearn a lot to do that.

I use home-row mods (well, bottom-row mods, actually) and apart from some combos having an extra key being held down, the idea that I'm now holding those keys with dedicated sensible fingers and without any hand movement means they aren't any harder than before. For example, what fingers are you even using when you type "ctrl+alt+shift+something"? Now, on my 36 key layout, I'm just holding bottom row index finger, bottom row middle finger, bottom row ring finger, maybe a thumb layer key which might be an extra button than before and typing the actual keystroke itself with the opposite hand. This has really helped me improve my opposite hand modifier skills as well as I often neglected to use right-ctrl on my traditional keyboard.

I use a 30% split keyboard as my daily driver for work as a software developer. I use a keymapping where holding the F key down turns the right side into a numpad plus some of the other punctuation, and holding D down gives me the shifted versions of all that. So I have to chord to get the esoteric symbols but I don't have to actually move my left hand from home row to chord. I don't think this is a very common way of doing things though. I'm not sure it's any better than using a bigger keyboard, but I'm used to it now.

I'm a developer and I use a (slightly modified) miryoku layout for my daily driver. I know not everyone loves the home-row mods, but I really like how I can use the layer keys on one hand to get all the symbols on the other. I have to move my hands waaay less than I did with a full size.

I ended up with pretty much my own entire layout. For the most part, I don't use layers, but instead use pairs of keys for symbols, numbers, etc. I also kept things largely where they are on a traditional keyboard, so that I'm not fighting against several decades of muscle memory.

The main issue with what I've done is that I'm kind of pushing past the limits of combining features with QMK. I use pairs of keys as modifiers (my left shift is 'E'+'D' for example), this key pressed is also '3'. If I roll on numbers, I end up with stuck modifiers. I've gotten fairly used to it, but it still hits me from time to time.

I do use a layer for things like cursor keys, though.

Many people are forgetting the simplest answer here. Just use a full size keyboard. They are abundant and cheap. They come with ALL THE KEYS and don't make you layer shift in order to efficiently achieve what you need to do.