More or less. As far as i know gVisor work with a host process that serves as a proxy for the os syscall and the child process dispatch the calls to the parent process through IPC which in turn execute it.

This is basically also how Chrome works, except that it serves otjer api's.

On Fuchsia, apparently the OS attach a binary which is a program on its own, to the binary that is executing and that in its "manifest" tell it will need a linux syscall proxy, which is this starnix that get stitched to the executable doing all calls in the same process.

On Fuchsia case this will end to be much more efficient because there will be no IPC communication involved just jumps on the code sector.