Honestly, i see little value in spending $150USD more for a Z790, when a Z690 can do for the most part all the same stuff.
All you need to decide on, is do you really care about an additional USB port and do you even have a use for an additional 8x PCIe 4 slot?
Because the DDR5 ram compatibility should be of zero concern to you, considering that the chosen ram is already within spec, not to mention it comes down to the CPU more so to run it, and a 14th Gen IMC is about as good as it gets.
If it was an AMD build, you should be concerned, but your on the totally opposite end of that spectrum for compatibility and with the latest BIOS update on a Z690, you shouldn’t be surprised if you could run even faster ram than its meant to be rated for.
Honestly, most haven’t said the way it is, the 14600k and its variants is a 13600k with an overclock, that’s all it is.
In your scenario, where you live, the 13600k costs more because it has the iGPU, which the 14600kf doesn’t.
As for gaming and bottlenecking, you can literally pair a 13600k with a 4090 and have minimal bottleneck when compared to a 13900k.
People still think of these as just i5’s but anyone who has one, will tell you they are way more powerful than what most have traditionally known as an i5.
No matter which way you look at it, there is always a bottleneck one way or another, there’s nothing you can do about that. But what you can do is try your best to ensure you’re more bottlenecked by the GPU, than you are CPU.
In the case of a 13600k/14600k/KF and a 3070 all the way up to about a 4070ti-4080, you will be GPU bottlenecked. So choose whichever suites your budget, either way you’re going to have one hell of a powerful CPU, just decide whether you want/need the iGPU or not.
I personally see the value in the iGPU myself, for that small bit extra in cost, it gives me piece of mind, knowing that if something happens to my GPU, I can still use the iGPU to have a display and troubleshoot, or at least still use the pc while the GPU is getting repaired or replaced.