At the end of the day, what you’re asking is “which formulas do I need to remember”. My opinion (and that’s all it is) is your actually making it harder for yourself by taking this approach because the list you’re going to come up with is still going to leave you with a LOT of formulas to learn. I’m not personally going to attempt to learn ALL the formulas.
From reading a lot of the posts, this is what I keep hearing.

“do the EOC questions, these are very important”

“I was shocked at how little I ended up using my calculator, I must have picked it up about a dozen times during the exam”
Based on this, if there wasn’t a question in the EOC on something and it involves calculating something, I’m not even going to attempt to memorize the formula. I’m sure there will be questions on the exam that I won’t know the formula to because of this, say 5 questions, but my thinking is that I’ll be more prepared for the other 235 questions because I didn’t waste a huge amount of time trying to memorize these.
My approach has been to determine which formulas are the VIP formulas (the formulas that are in the fat bit of a normal distribution curve I guess you could say) and really focus on memorizing those and practice lots of problem that involve those formulas (i.e. stuff like the dividend discount model, CAPM, Dupont, etc). By repetitively doing QBank exams, I’m narrowing down what those formulas are. Inevitably, I’ll always miss a few questions because there is some weird calc with a formula I can’t remember that comes up (the formulas that I think of as being in the tails). With these, I make a mental note that I’ve missed it, and if it keeps coming up in QBank exams and I keep missing it, then I make the effort to memorize these formulas.
Another approach of mine has also been to understand concepts rather than formulas and from understanding a concept be able to derive a formula. I find this condenses what you have to memorize. For example, I don’t think of Beta as a formula, I think of it as the covariance of the asset to the market to the variance of the market. This is a concept to me, not a formula, and I find it easier to memorize.
Like I said, this is only my personal approach. Happy to take criticism though.