This is pretty interesting since you're basically locked out of using anything from outside the surface until after you've "solved" everything. The only outside tech that helps marginally is some of the productivity research, even then it's not a huge help since you're more or less dealing with yellow belts and research prod is disabled for most stuff.

One thing that could be improved on, is the embargo should include construction bots, but you can find some old construction bots in the ruins scattered around.

Yes, it's a bubble world that only connects with your space empire after completion. Each of the mid-tier vanilla planets do contribute tech that can help, but only marginally.

Construction bots can't come from ruins because players would expect to be able to recycle them, which would break the mod. Or even if they didn't, it would make the messaging around recycling bans a lot less clear.

Now that you mention it, being able to recycle the construction bots would basically completely bypass the cerys endgame of making the electric engines (though you'd need 200 of them so if they were from ruins and were recyclable you'd end up way short if each one only had 1 or 2). I didn't even think to try that. Another thing I noticed (correct me if I'm wrong here), I believe you can technically softlock yourself from making any progress on cerys if you collect all processing units from the ruins and use all of them (or destroy them) without crafting any recyclers. It'd be pretty hard to do that by accident though.

It’s not clear what you’d be crafting with blue chips, but the combination of finite playspace and minable ruins can indeed lead to theoretical softlocks.

Generally, mining all the ruins when you first land is a poor strategy on a first visit to Cerys, as the remaining ruins provide a pressure valve if your research acquisition by other means is stalled.