When this first came out I checked on my Pixel 7 which is on A14 already and I didn't have the apps available either.
They are now available.
So yeah, it's almost certainly on the app developers who didn't target the new API version available, not Google. New Pixels launch with new versions of Android, but you can validate the same issue on older Pixels who have already upgraded to the new Android version.
Google Messages (RCS app) does that. It even works from iMessage to Android but that is just because Google parses the SMS text that says they reacted that iMessage passive-aggressively sends and makes it appear correctly. It's not following RCS protocol, it's basic text parsing is all.
Incidentally, Google also started sending the same pass-aggressive reacted SMS messages to iPhone users for those using those RCS features, so now Apple gets the messages Android users had to deal with for years (and still do, if they aren't using Messages). I don't know is Apple is doing the same parsing or not as Google, if they aren't then somewhat ironically to Apple's intention Android now has the better react experience.
Revanced?
Revanced can't exist as a standalone app to be installed like from a store. Google would nuke it. It has to be a patcher. Original Vanced was a standalone app and that is what allowed Google to nuke it from orbit. It's arguable that Google ignored Vanced until the developers got money grubby and tried making NFTs, but the method they used for takedown was DMCA since it was their app just modified.
This is the same thing as ROM hacks, randomizers, etc and why they include a place to upload your own copy of the ROM rather than providing their own. Reverse engineering and modifying are legal, distributing copyright source, binaries, or blobs without the rightsholder permissions is not.
They also do have a repo for it, as well as the offshoot apps like Revanced manager, other app patches, etc. The fact it's not at the top of Google results is a Google-and-SEO problem, not a Revanced problem.
If you want a one and done app install then something like Newpipe is what you want, which is built completely on its own. Revanced is explicitly not that, it's the stock app hacked up. IMHO, Revanced is a nicer experience, but they are two very different experiences and approaches.
This whole thing isn't on Google. The app developers didn't update their target API so they were not available. My Pixel 7 is on Android 14 as well and they weren't available either until it just got fixed.