There are about a zillion ways it could prove to be impractical. Apatite is a crystal, and presumably this lead apatite is also a crystal. We also don't know if it can be deposited in a useful thickness; the samples tested so far were created by gas deposition on glass. Can it be built up to a useful thickness, and maintain its superconducting properties? All unknown.

But, real progress always comes in small steps. It's exceedingly rare for any discovery to result in a useful product immediately.

I don't know if it's real or not. I've downloaded and read the papers published; materials science isn't my field, so all I can really do is look for egregious falsehoods set in place to bulk up the word count. I didn't see anything obvious.

I think it's interesting that there are several major scientific institutions replicating the experiment and running serious analyses of the outputs (First-principles study on the electronic structure... https://arxiv.org/abs/2307.16040) (Origin of correlated isolated flat bands... https://arxiv.org/abs/2307.16892). Additionally, replications of the experiment are showing positive results (Meissner levitation of samples they synthesized themselves).

http://koreascience.or.kr/article/JAKO202315638176796.page

https://arxiv.org/abs/2308.01516

If the big, famous labs are putting time and money into replicating the results and doing serious analysis, and are getting positive results (as well as successfully replicating the experimental results), that's a pretty positive sign.

The fact big labs are replicating and still haven't disproved it makes LK99 more likely to be real - a disproval would take longer and carry lesser reputation cost if they get it wrong (higher rep cost if they confirm LK99 is working and turns out it isn't)

It's either real or its not real. So yeah 50/50 chance.