Nearly all of them can and do stand alone, although I've not seen anyone called
Tilda or
Fran who was named that at birth.
I think your average non-namenerd probably thinks of
Sadie &
Liam as names in their own right, & isn't even aware of the connection with
Sarah or
William - & both my husband and myself had Victorian relatives called just
Eliza.
I wouldn't personally use any of them as full names though.