dnd 5e – Can you throw Insect Plague with and / or without crying in another room?

So there is one possible scenario in my game. I've "accidentally" given my players a very tiring position that could make a detour from a pretty grueling fight if they think they're using it. It's a small prison with a heavy, sturdy door to block. I have the idea that one of the enemy spellcasters might throw Insect Plague into his room, as he is familiar with this area and the spell is not a "point you can see" but a "point you choose within reach." ". , I would use this as a tool to force them out of this place and hopefully offer a more interesting fight.

Since this is a summoning spell, I can imagine that he summons the insects from that point. The rule on page 204 of the PHB, which states that you need a clear path to the destination, does not seem to be as if it would apply it?

To be able to target something, you must have a clear path so that it is not possible
behind total coverage. When placing an effect area at a point
can not see and an obstacle like a wall is between you and the one
Point, the origin arises on the near side of it

The wording makes me think that the wall would block the spell. In this case, the caster also has access to a magical item that gives him the ability to cast the spell. Knowing they are in this prison, he could spawn the sensor inside and then have visual contact to throw Insect Plague.

However, there is a problem here because both scrying and insect plague require concentration. Would it still be possible for him to throw Insect Plague, but to immediately break the focus on scrying, or would that be impossible?