There are many Bally EMs in the silver age with this feature prior to the 1970s. Nip-It does not purely qualify as the playfield bonus is collected at ball drain, as it is added to lighted scoring. One of the earlier games is Capersville (1966), but many bonuses are collectable early such as Dixieland or Dogies (both 1968) or Joust (1969). Certain playfield ruleset conditions MUST be met. I would have to go through the entire list to find them all. I only specialize in Bally games, not Gottlieb or WMS, so there are certainly others.
There is no such animal as a "solid state EM", except in rare cases where you have a pure prototype conversion. It might look or play like an EM or even have components, but if a game operates under the electrical logic of an EM, it is an EM, a game cannot be classified as a SS. The same goes for a SS with ICs but still might have things like rotation score reels controlled by solenoids (or even motors), this is still a SS. This is a separate topic in itself and gets into some technicalities.
A good example would be Fabulous Fantasies (Herb Silvers) King of Diamonds Gottlieb remake. This is a SS, not an EM.
Another would be Stern WNBJM (not Whizbang, as the original was a retheme EM) as this is a "conversion" but also SS.
