Hop is wit them.
Them Russians got tf up outta there quick b4 the Army...who showed up late as all hell...got there.
I think either he found a way to sneak outta there b4 the explosion.
Or...the Russians snatched him on his way out.
OR...he could've dipped in the portal b4 it closed to escape the blast. So next season when El finally regain her powers...she realizes Hop is alive, and was stuck in the upside down this whole time. Therefore launching a plan to get him out.
How?
The laser was still going up until Joyce turned the keys. And the explosion was instantaneously