Backstory: I started an 5E Eberron campaign before the COVID closures started, and part of what I did before starting the campaign was to get an idea from the players what they were looking to get out of the setting - like, did they want the political machinations, exploring crazy ruins, etc. They said that they were looking for more of the Indiana Jones feel, which - to be honest - I was grateful of because it requires me to remember less in terms of NPC plans/plottings.
The other thing that was volunteered was that one of the players was tired of "saving the world from demons," which I could understand. Our group isn't really big on just "hexwandering," so I came up with a different idea of Big Bad Guys to eventually threaten the party/world with.

As Eberron is such a magic-heavy setting, I got to thinking that having no-crap-sci-fi technology would be something that would more or less be completely alien to all involved; specifically, aliens were supplying tech to a particular group, a genasi faction that was looking to destroy various larger magically powered vehicles to "free the enslaved elementals."

The aliens in question don't really give a crap about any of that; they are solely interested in "expended" or broken dragonshards (which they will eventually be referring to as the super-creative "ultranium"), which they require to power their damaged star-drive, without which they will eventually lose power and their orbit around the planet will degrade and the ship will crash.
The aliens are going to need ridiculous amounts of such shards, like literal tons of material - to the point where them obtaining the amount they want would exceed what is actually available. In order to try to get this sort of supply, they are the ones who are largely responsible for the catastrophe in Cyre that created the Mournlands - it was basically a way to break a bunch of stuff at once for them to harvest without much issue.

In any event, I plan on using some of the baddies (the Wroth) from "Dark Matter" from Mage Hand Press as these aliens, and I figure that I'll need two areas for the party to eventually muck about in: the in-Cyre base that the aliens use to get the material to the ship (via telepods), and the starship itself.

To that end, I'm trying to find a couple of adventures that might include interesting encounters for a high fantasy party to encounter weird alien crap. I don't think I would be using them whole cloth, and I estimate that them encountering this stuff is going to be far off enough (at least another two months of us playing) that I won't really have time to make something up all by my lonesome.

Ideally this would be some variety of D&D (to include offshoots like Pathfinder/Starfinder) just because it would make conversion to 5E easier, but if the ideas are good enough I don't think I'll mind if I have to make up the numbers myself (as I'm probably going to be inserting creatures/baddies to fit).

Anything jumping to mind?

https://youtu.be/GgRp9ZvunDc

Occurrence at Howling Crater is a decent choice. Available on Drivethrurpg.

Ooh, that does look promising.