GL-X750V2 space issues, WHY?
It has space issues because it only has 16MB NOR flash, for another couple of bucks it could have had 32MB and many of us wouldn’t be having major issues with this router.
Have you set the Mount Point to “Use as external overlay (/overlay)” for Device /dev/sda1 in the Luci GUI? That should allow the micro sd to be used for plugin storage.