Psalm 88:10 Wilt thou shew wonders to the dead? shall the dead arise and praise thee? Selah.

God did indeed show wonders to the dead. Those who died in faith, before his coming saw something wonderful, Him, coming in glory (he was glorified on the cross) and raising them from death to life (Matt 27:53).

But more than that, the dead on the earth also beheld/behold his glory. I.e. those alive physically but dead spiritually.

His word is preached with signs and wonders following, and we were/are all dead prior to hearing and receiving his word. Now that we are alive in him, we can praise him and speak HIS Word so others may have the opportunity to hear and come out of their graves.

John 5:25 Verily, verily, I say unto you, The hour is coming, and *now is*, when the dead shall hear the voice of the Son of God: and they that hear shall live.