rclone --vfs-cache-mode writes mount onedrive: ~/OneDrive & was the command I executed to mount my Onedrive on my Linux box. 

Error message was:

2024/04/27 15:37:08 Fatal error: failed to mount FUSE fs: fusermount: exec: "fusermount3": executable file not found in $PATH

•  sys-fs/fuse
        Latest version available: 3.6.1
        Latest version installed: 2.9.9
        Size of files: 1,142 KiB
        Homepage:      https://github.com/libfuse/libfuse
        Description:   An interface for filesystems implemented in userspace
        License:       GPL-2 LGPL-2.1

Apparently, I hadn't pulled in the latest version of fuse elsewhere.  As a result, I couldn't mount via rclone. 

'emerge fuse' fixed the issue, but it probably should have the dependency on FUSE 3, no?