The shuttle itself completed several atmospheric and one orbital flight, demonstrating autopiloted runway landings from orbit.

The reusable booster technology was just planned, though. The project was cancelled long before they could be tested. I'm not even sure there were any finalized specifications.

I don't agree - https://en.wikipedia.org/wiki/Energia

There were two launches - the first of a "fully armed and.. oh" space battle station (I shit you not), the second of the Buran.

Yes, and? Both launches had the Energia in a fully disposable configuration – the launcher was never equipped with the hardware to recover the boosters, nor did the hardware exist.

Only the orbiter returned, like with the Shuttle.