I’ve heard good things about IKEA electronics and white-goods also; for instance their LADDA batteries are apparently Eneloops, their dishwashers are/were Bosch, and they partnered with Sonos for their speakers also.
Costco apparently does quite similar with their Kirkland own-brand products - but at least here in Australia they haven’t offered (m)any electronics yet.
4K content on streaming is pretty terrible - so I can’t blame you for that opinion.
But comparing a 1080p Blu-ray to a 4K copy makes it a lot more noticeable, akin to watching a 480p DVD next to a 720p Blu-ray.
Lines are crisper, you can notice a lot more detail (skin texture on close-ups), background objects are clearer - nothing exactly revolutionary, but still an improvement nevertheless!