If I make a snap that serves as a remote command execution agent, can I grant it the permission to run snap set other-snap var1=foo?
an equivalent to the snap set command would only work via the snapd REST API, but to get access to this you would have to use the snapd-control interface with is restricted to only be used in brand stores …
alternatively you could make snap1 provide a dbus interface that snap2 could use …
or you could use some listening socket in snap1 (with i.e. a script attached) that you make accessible to snap2 via a content interface …