Honestly there are surprisingly few enablers in the regular tech tree. The food buildings and apartments come early, and the factories also come before the point where you need a second one, and you can import your factories, so it is by far not as big a step as getting a new building. I never really use smart homes.
That leaves the fusion reactor, the big science building, the university and the scrubbers, which are all useful... but that is about it all the way to the wonders.
This makes the tech tree look much smaller, the really noticeable part. The rest really is filler, nice to have, but all stuff I research pretty much on a lowest-cost basis without putting much thought into it.
First: you have forgotten all spire buildings, all domes, the shuttles, the atomic accumulator, the meteor defense system, the heaters (which admittedly also comes early) and the vaporators.
I would argue that stuff like deep scanning and being able to access those deposits is quite a significant step, as they can condition your expansion quite a lot.
Also, upgrades are something I didn't use to consider much, but given that they don't increase maintenance costs, and that in most cases they cost fuel, energy or polymers, all stuff that can be produce limitlessly, they are much more important in difficult runs that one might think at first. Anything that cuts down maintenance costs is great in my book. Low-G turbines is something that I tend to rush early
Finally, there is stuff like waste rock liquification or autonomous sensors, which while don't "add" new stuff significantly affect how these work (by the time I have autonomous sensors I generally take a rover and a transport and fill the map with sensors, and WRL is a tech I tend to rush when I'm starting to have trouble with all the waste rock).