There isn't a single device that is going to provide adequate coverage - unless it is 4000 sq ft of outside space
As others have mentioned, you need some sort of managed or mesh wireless network. This means that you will have multiple devices vs an "all in one" solution. You can likely keep your existing "all in one" router that you already have and simply turn off the wireless access point functionality of that device. It will continue to act as your network's router and a switch, but it will not provide any wifi network. Then you will need to supplement this router with several wifi access points that can work together to provide coverage in your dwelling.
When a manufacture uses the term "mesh" to describe their wifi access points, it usually means the devices will connect to each other wirelessly. This might be easier to install (because you don't have to connect each device into the network with a hardwire network cable), but it also means that the throughput may be slower. This is because the devices act as repeaters for other devices. So a device might be transmitting all the data from all of the wireless devices nearby that are connected directly to that AP, but it might also be carrying all the wifi data from other mesh devices as well.
If you get a hardwired solution where each wifi access point is connected to the network with it's own network cable, then each access point is only responsible for transmitting the data for the locally connected wireless devices and it will never have to re-transmist data from other wifi access points like a mesh network might do. This generally results in a faster overall wifi network. The good news is that many manufactures systems allow for both types in the same network. So for example if you have three wireless AP, but can only hardwire 2 of them, you can likely connect the third one via a wireless mesh. This will be faster than using a mesh connection on all three devices, but might be slower than it would be if you were able to hardwire all three devices.
One thing to keep in mind if you are building a new system is to look for "wifi 6" access points. I use Ubiquity wireless APs at my primary residence and TP-Link APs at my parents house (who rely on me for all their "technology" needs) and while I have begun replacing access points with wifi 6 devices, most of the other APs are older and don't support wifi 6. It's not that big of a deal (I'm not maxing out the older transmission speeds), but I certainly would not buy non Wifi6 compatible devices today. (Most of my APs are probably 10 years old).