@BlankHotel The processor can be upgraded to anything from the same generation, so i7-14xxx or i9-14xxx. You'd probably need a more powerful CPU cooler for the higher-end SKUs, not necessarily an i7-14700 but anything above that. I'd have to look up benchmarks and don't know the specs of the cooler that comes with this build.
The graphics card could be upgraded in theory, but for an RTX 4070 or higher, you'd need to upgrade the power supply as well. A 500W PSU isn't sufficient. I have no idea how much power the RTX 5060 or whatever Nvidia ends up calling it will use, but it might work fine; the 5070 or equivalent will almost certainly need more.
For the monitor, the most important detail is that it has an IPS panel, the highest quality. Next I would suggest looking for something with at least 300 nits (candelas, or cd/m^2) brightness; 250 is fine in a darkened room but not ideal under lights. If you're willing to spend a bit more for the monitor, a 2560x1440 resolution would look great, and your GPU can certainly handle the load. For the size itself, whatever feels comfortable and fits on your desk is fine.
If you're not ready to buy a new monitor now, you could pick up a good used one for cheap on Craigslist or Facebook Marketplace. Monitors lose their value pretty quickly, so a 1080p IPS monitor that's a few years old could cost very little and last you until you've picked out the model you want.