Input devices almost never use USB 3.0. In fact, most manufacturers save money and don't shield the cable, forcing half-speed USB 1.1, which is enough for all mice and keyboards - less than 50 kb/s of the available 6 Mb/s is required even for 240Hz polling. High-end mice might have USB 3.0 (9 pins instead of 4 in the plug) but there should be no practical difference between 3.0 and 2.0 speeds. The polling rate will most likely be identical and the microsecond difference between how long each takes to transfer the data is likely way lower than lag from the mouse's wireless connection.
Just use any USB 2.0 hub, even $2 ones from AliExpress will work the same as high-end ones. Most are sold with 4 ports because that's what their standard generic chip does. You probably have one lying around or built into the monitor. You're unlikely to cause interference so just choose any spot with strong signal to the desk area, not necessarily line-of-sight: if the mouse works everywhere within 2 meters from the intended area, then the intended area will have good signal and minimal chance of dropout. The lag or polling rate does not decrease with signal strength unless you count extra nanoseconds the radio waves need to travel.
The only difference is when you need another port for high-speed applications such as mass storage devices or MTP with your phone, at which point just plug them directly into the PC for max speed.