In principle, you can use the stick for this, but this is a waste. Normally you use a stick with a maximum capacity of 8 GB that has fast read and write rates.
With Windows 11, it's questionable whether it's any good anyway. Windows 11 has relatively high system requirements and newer PCs would be slowed down by Readyboost.
In principle, if you have installed an SSD instead of an HDD, Readyboost is useless or even a hindrance. It is useless on devices with more than 4 GB RAM and a Windows 64-bit installation and is generally not even offered by the system.

I have no answer to that question, as I have no experience with readyboost. All my systems have enough RAM, so that paging performance is not an issue for me.

My motivation for this USB storage stick is that it supports the UAS (SCSI) protocol vs. the older BOT protocol, which is just perfect for my RASPI 4 systems, as the result is a faster system. Additionally, this USB storage device by Kingston is quite reliable and offers a good value for its price.