Disney, Netflix, Amazon all stream in 4k, the latter two create content in 4k. Not as good as the discs, but still an improvement over bluray. And for those whose TV size or viewing distance is such that the resolution improvement is hard to see, the color improvement is not, esp with the OLEDs.What makes all of this truly crazy is that for four years in a row the biggest selling home entertainment product has been 4k television. Today, 4k TVs can be quite inexpensive, and I would say comprise the vast majority of all TV sales in any particular store. So, with all of these 4k TVs in peoples' homes, where's all the 4k content? Go figure.
One element holding back 4k discs, aside from the general trend towards subscription models, is that quite a few movies are created in 2k to enable easy CGI, so their uplift to 4k is hardly different from the TV doing it on a bluray. Still the HDR gains, but people are reluctant to pay extra for the same effective resolution, and lots of websites named '4k real or fake' have emerged.
The older movies, filmed in actual film, have strongest potential. For newer, need to read those audophile type reviews.
And of course, if the movie is a rom com, HDR and resolution are kind of irrelevant. Just get the blu-ray. Me personally, can't slum it at DVD resolutions anymore.