[Typhus]

In the description of the Prodigal Spell ritual, it notes that an indirect spell requires a clear (ish) path to the target.  This suggests the target must be outdoors, but no additional detail is provided.  Seems to cause a lot of questions around practicality of the use of this ritual, but maybe this is a "change blindness" thing and this was addressed in 5E?

What's intended here?  If I know I am the target of a sending somehow, and I duck into a building, am I thus immune to the spell unless someone opens the door?  Does it hit the door instead?  Can it hit random people on it's way to me, like a speeding truck?  Can I throw someone in front of it at the last second once it zips into the coffee shop?

Some of these questions are facetious, yes.  Just illustrating the questions that could arise, with so little apparent guidance on how this is pictured as happening in the world.  Any input is helpful.

[Stainless Steel Devil Rat]

I'm not really seeing a problem here.  The language, for the record:

Direct combat spells travel to the target
in astral space. Indirect combat spells travel to
the target in physical space, requiring a clear (but
not necessarily straight) path in the physical world
between the ritual team and target in order for the
spell to reach its destination—the spell flies from
the foundation to the target, dodging any obstacles
in its path.

So, as you noticed, Direct spells just Zort the target.
Indirect spells must travel from the point of origin to the target's location.  This is simply still true for rituals, is what it's saying.  If the guy is in a building, then your ritual fireball flies in through an open door or window.  Are there none? The guy sniffed out that he's walking Ground Zero for a ritual combat spell and hid in a bunker? Ok, then the fireball must blow through the barrier.  Maybe it won't manage.  Probably should have used a Direct Combat spell on that guy instead.

[Typhus]

So it should attack barriers instead of just failing, in your reading?

[Stainless Steel Devil Rat]

So it should attack barriers instead of just failing, in your reading?

I'd adjudicate it at my table as failing if the ritual team is inside an enclosed space with no avenue for the indirect spell to begin its journey.

OTOH, the ritual team cannot control where the target puts himself over the course of the hours long ritual.  Rather than worry if the target ever walls himself off at any point, and if so when... I'd just not even worry about the target's condition until the ritual is finished. At that instant, WOOSH the spell launches and magically homes in on the target. The spell doesn't just go in a straight line... explicitly it seeks out the shortest unimpeded path. If there is none, then in that case yeah. It tries to blow thru the barrier.

If you happen to know where the target is, and is walled off, I'd allow teaming up with a sniper or a rigger to blow a hole in the wall just as the ritual completes