One thing to think about with mesh systems is that the repeating from one node to the other is also via wireless, so you may encounter roughly the same issues with a single node vs multiple mesh nodes if the nodes don't have good communication with each other.I strongly suggest installing a mesh system. You will have fall off from point to point but it will perform much better than what you are currently experiencing.
I have an 8 year old ASUS router in my basement. WiFi was always crappy in places upstairs. I decided to switch to a $300 2-node eero mesh system. I tried placing the eero nodes in about 10 different locations relative to each other and could never get the WiFi speeds I was looking for.
I ended up returning the eeros and purchased a 2nd identical 8 yr old ASUS router for about $30 on eBay. I wired the two routers together via a 100 foot ethernet cable (drilled a hole out my basement wall, wrapped the cable around the outside walls of my house by just tucking it under the siding, drilled a hole in my upstairs sun room and installed an ethernet jack in the wall) and enabled the built-in mesh feature. I'm super happy with the results - my WiFi speeds are very good throughout the entire house now.