With you planning to upgrade to a 3000 series RTX then I would focus on the areas you already are. I’m not a fan of the 9700k because of its lack of multithreading. It’s a great CURRENT CPU but how long will you plan t use it and how long before it falls behind a 3700x/3800x or a 9900k? Idk but I’ll never recommend that CPU regardless of how well it performs NOW. I’d get any of those 3 over a 9700k personally. Regardless it will be a good upgrade for you, just a weird choice with 8c/16t CPUs on the market in the same price range.
Monitor is something that I upgraded recently and did a LOT of research on. Anything branded GSYNC is immediately a waste of money IMO. During my research it was interesting to me that Nvidia started certifying Freesync monitors to be Gsync compatible. What this means is the monitor uses gsync with the Nvidia GPU without the huge price hike. I went with an Acer xg270hu for $300 and it has performed flawlessly. Couldn’t see 1 reason to pay another dollar.