This is similar to $editcontext.editType.
Add editEnviornment property to the $editcontext property for the Form Calculation and Constraint Arcade Profiles (e.g. $editcontext.editEnviornment). It would return either "Web" or "Mobile". I could write it to an attribute in my schema to store this value or use it to inform other actions.
Generally, I might want to know where the edits are coming from... the JS API Form -> Web (e.g. Map Viewer) or Mobile (e.g. Field Maps). I could then know which edit environment was used for the last edit (written to an attribute) or which environment is being used for the current edit.