Hello, my pal, there is no native BitLocker unlocker coming with macOS, so you need to make use of a third-party BitLocker unlocked to decrypt your wife's USB and then copy files from it. I'd like to share the unlocked that I use on my Mac, that is, iBoysoft BitLocker for Mac.
iBoysoft BitLocker for Mac is a one-stop solution to manage and use BitLocker encrypted drives on Mac. You can open BitLocker encrypted USB drives on Mac easily. On top of all that, you will gain full read & write access to BotLocker-encrypted HHD, SSD, USB flash drives, SD cards, etc.
It can encrypt drives with the BitLocker encryption method and supports encrypted NTFS, exFAT, and FAT32 drives on macOS Ventura, Monterey, and M2, M1, M1 Pro, and M1 Max devices.