well, Ubuntu Core is used to drive embedded systems, kiosks, industrial, robotics, automotive, digital signage, IoT, point of sale … do you expect mewa to be used in either of these ?
as alex said, the home interface itself is auto-connected on most distros that use a graphical desktop, you do not need to explicitly ask for it …
for hidden dirs under $HOME you will need to create one personal-files interface in your snapcraft.yaml for each hidden dir you want to access. auto-connection is granted if your snap is clearly affiliated with that dir … i.e. ~/.mewa or ~/.config/mewa … the name of the interface should be the path relative to the home dir with slashes replaced by dashes (taking the above example you’d create a
dot-config-mewa personal-files plug entry in your snapcraft.yaml)