Curious if anyone else reading this knows about the equivalent of US "pink sheets," publicly traded companies that have either never been listed or have been delisted due to low share price / market capitalization.

Here in the US, you can buy publicly traded companies in the US for a song; in fact, that was the source for the "acquiring" company in a lot of those reverse-acquisitions of the late 2000s / early 2010s: publicly traded companies that had a ticker, but were basically defunct. A company that wanted to go public without the scrutiny of an IPO process could "buy themselves" with the tiny, publicly traded company, thereby getting a ticker and access to retail investors. (This was not a good phenomenon, fwiw, though it definitely anticipated the SPAC craze... which was also not good, for similar reasons.)