iOS shoots HEIF natively I think.

Raw photos probably are shot in DNG. DNG "images" are popular for raw images because theyb can be losslessly converted from to the camera raw formats like the Nikon's, and DNG is open source and royalty free.

The iOS camera format control is one of the most confusing UIs in iOS. It first asks you to select between high efficiency and most compatible (HEIF vs JPEG). Then it asks you whether you want ProRAW. Then under ProRAW it asks whether you want JPEG lossless, JPEG XL lossless or lossy. That doesn’t even include the in-app control of JPEG Max (which AFAIK is just 48 MP JPEG).

Old doesn't mean outdated. TCP is ancient and we still use it for a bunch of stuff.

JPEG is good enough, not encumbered by IP concerns, and universally supported. That makes it better than an alternative that is "better" in a less important dimension but worse in broad support.

Apple bought Pixelmator/Photomator last year, though I have no idea what their roadmap looks like or if they plan to turn those into native apps or OS features.

Every camera manufacturer has their own RAW format. Apple produces a general-purpose RAW engine that can process many of those formats, but not all of them, and with a few notable misses, as noted in the linked article. The RAW engine is considered pretty good, fast/efficient, but overly aggressive on some of its defaults (noise reduction to the point of detail loss). The native Photos app also doesn't have many advanced RAW tools for editing the RAWs.

I posted my current workflow in a sibling - basically, I use Photomator for edits (Lightroom competitor, now owned by Apple) and Photos for library management and sharing. Works fine for me as a enthusiasts, but unlikely to work for a professional (and probably not for enthusiasts who like tinkering with their photos more than I do).