Our usual method of determining what everything is ..
Easiest is to use a net scanning tool like FING or iNet .. both have free versions for iOS.
But it is not always possible and lots of unknowns will still show up.
So change the password on your wifi. When you do that everything will stop working. Add back devices one by one.. noting carefully the associated MAC address.. if it is not already on the label write out a label and stick it on the device.. but MAC address is often part of the serial number or printed directly on the item.
With the huge number of iOT devices around now it is becoming harder to keep track.
Other than the usual assortment of computer gear, printers, scanners, APs, storage, it is easy to forget smart TV, door bell, baby monitor, light dimmer, security cams, thermostats, garage door opener. We are getting to the point where the fridge reports its contents and the toaster and coffee maker are linked for reasons I cannot fathom.