Unexpected Transposition

[The Total Package]

If I am Grabbed or even worse swallowed whole, can I use this ability to swap places with a willing ally even if I cannot see them but they are within 30ft?

https://2e.aonprd.com/Spells.aspx?ID=1024

[Conscious Meat]

Nothing about the spell excludes it from the usual rules.

https://2e.aonprd.com/Rules.aspx?ID=2237&NoRedirect=1

Quote:

Some spells allow you to target a creature, an object, or something more specific. The target must be within the spell's range, and you must be able to see it (or otherwise perceive it with a precise sense) to target it. At the GM's discretion, you can attempt to target a creature you can't see, as described in Detecting Creatures on page 434. If you fail to target a particular creature, this doesn't change how the spell affects any other targets the spell has.

Quote:

You usually need an unobstructed path to the target of a spell, the origin point of an area, or the place where you create something with a spell. More information on line of effect can be found on page 426

[Finoan]

Grabbed also causes the Immobilized condition. Immobilized prevents using actions with the Move trait.

But nothing in Unexpected Transposition or Cast a Spell has the Move trait. Unexpected Transposition has the Teleportation trait.

So you could cast it in response to a Strike action while you are grabbed and it would work fine.

Personally I would rule that the other target of Unexpected Transposition would also gain the Grabbed condition the same as you had when they arrive at your position and you would lose the condition. That is not specified in the spell though.