[uli]

With the Reading List add-on, create "auto populated list" for each device, in the column update section have: when changed, add/remove, #device = reader_name

#device:reader_name // on specific reader
#device:true // on any reader

Or instead just use the add-on to sync lists to a specific device... so a saved search would just be a reading list..

Make auto-pop lists with search: #sendto:any, kobo, kindle, etc
JobSpy has an option to quickly tag books with: 1, #sendto=any, 2 #sendto=kobo, etc

Example:
Edit: (for any device have the list add only, not replace.)