You could do this; just copy your home folder to the USB, but you will have to edit /etc/fstab on every machine that you plug the USB in to so that it mounts the USB as /home or /home/username. You will also have to make sure every machine you plug the USB in to has an entry in /etc/passwd and /etc/shadow for your user and that all those user entries have the same numeric ID. Then there is the risc of different computers using different versions of software, which may cause trouble with your config files, or different computers running different distros, or DEs, which might cause trouble with your ~/.xinitrc. (Took me ages to get OpenSUSE to accept my Archlinux .xinitrc file.)
Is this feasible if you want to carry your user account with you wherever you go? No.
Is this feasible if you want to have the same user account on all your home computers and your computer at work? Maybe, but you might as well use an old computer as an NFS server from your home. This is a lot safer and easier.
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