You will quickly end up researching mechanical split keyboard market and start convincing yourself that 500-1000€ is not that expensive (sic!).
I made an adventure into mechanicals, around half a year on research and getting used to it. Configurability is amazing. Quality great. Noise was not a problem.
Ended up going back to some flat (laptop-like) dell keyboard and a vertical mouse instead. Because my hands started to stiffen up, hurt, the typical stuff. Keyboards were too high (with normal keys) and too expensive+weird (with low profile keys). I tried adding dedicated palm rests, changing habits a bit, changing bindings...
In the end I'm considering buying MS' Sculpt ergonomic keyboard again (it's the one that's actually split, low profile, with optional negative tilt. I think it's only sold with a mouse). It has a lot of flaws, but fatigue was not one of them.
What I'm trying to say: you may spend a lot of time, effort and money and still feel miserable. There are amazing builds out there, but don't forget non mechanical options exist.