Title is essentially my suggestion - would it be possible to add an option in startup settings to allow users to change the weight of the science pack to be the same as the other science packs to allow for compatibility with end-game save integration?

I've been enjoying the interplanetary logistics of SA, and after beating the base game in my current play-through have been starting to incorporate the most popular planet mods. After completing Cerys (amazing btw, from the mechanics to aesthetics, great addition to the game) I was hoping to tear-down all my existing builds and re-structure the entire surface for the sole purpose of making reverse engineered science packs to then be shipped to the "central labs" on Nauvis.

Is there a reason for not being able to ship these off-world?

It's an intentional design choice. The "cerys experience" is mostly segregated from the rest of your playthrough by design. There are a few rewards you can take off world though, like the special modules, and the nitric acid blue chips recipe uses slightly less green chips (though outside of aquilo you would need to import nitrogen rich minerals to be able to come up with the ammonia for nitric acid). And of course the productivity researches that have to be done on Cerys.

Btw, if you want to "mod the mod" to remove the export restriction on the cerys sci pack, the regular labs DO NOT have a slot for them so they still won't work. You'd have to mod that as well.

Now that late-game Cerys has additional integration with your solar system in v4, namely the plutonium needed to power radioactive modules, it's not a crazy idea to relax the surface restriction for Reverse-engineered science packs and let players export it. The rename from Cerysian science contributes as well.

I'd like to receive more considered feedback on this. If someone wants to write a third-party mod and try it out, that would be great too.

I wouldn't have anything against a toggle, but the default should be "what happens on cerys stays on cerys." What makes this mod unique is the fact it's a little sandbox sidequest.