Do you intend to do anything else? High FPS isn't important for your use case from what I can tell but it is nice for some games (e.g. first person shooters). For a predominant purpose of using Excel, what is useful is the ability to see 'more' data through both higher resolution (i.e. pixel density) and the aspect ratio/size of the screen.
I previously had an Acer X34 34" ultrawide (21:9) 1440p and found it was immensely useful for my job of reviewing Excel models/documentation - the higher resolution meant you could zoom out and still have more detail visible (compared to a lower res monitor when you zoom out and the text is not legible and becomes a bit of a pixellated blur/mess), and the ultrawide aspect ratio meant that whilst most people format their Excel models to fit a standard 16:9 ratio, you get extra width in case things are a little bit too wide.
With a $500ish budget, I'd consider something like the Kogan 34" 3440x1440 ultrawide
https://www.kogan.com/au/buy/kogan-34-wqhd-curved-219-ultrawide-100hz-freesync-monitor/
If you were wanting to spend more (like alot more) you could go for a different ultrawide monitor brand potentially a higher resolution, or a much larger monitor. I personally upgraded to a Samsung CHG90 which has a lower resolution (3840 x 1080) monitor but super ultrawide 34:9 aspect ratio over 49" to improve my multitasking.
Following on from Brent's point, agreed multiple monitors can also be a great way to improve productivity but try to get two matching monitors if you're going to go down this route.