ACC is an industry standard and was when Apple adopted it. Just like the transition to USB, Apple just happened to significantly increase the speed of adoption of an objectively superior standard.
iMessage is a bespoke messaging app (at this point). I don't see how SMS/RCS enters into it, other than that the Messages app also supports bog standard SMS (and in no way, shape, or form extends it in a way that introduces friction, unlike RCS).
AirPods were initially bog-standard Bluetooth and still support bog standard bluetooth without any undue friction.
AIO vs. components. I'm not sure how that even entered into the discussion of supporting standards. How does an AIO take something open and standard and tweak it so it can't be used by something not Apple?
App "stores." Same as previous point. They didn't even set the precedent. See gaming consoles. Or Steam. Or Epic. Or…
On the flip side.
IMAP,
iCal,
vCal, PDF, JPEG, HEIF, MP4, EPUB (if you ignore FairPlay DRM, which is no worse than Adobe's DRM, but it does support non-DRM EPUB with no undue friction). Sorry they're not all linked, I got tired of looking up links to the canonical standards Apple uses in its products. There are more esoteric ones, too, like RTF, that Apple supports the standards of, and pretty thoroughly, without extending in a way that breaks interoperability. HTML, HTTP, SMBA, NFS, NTP and probably more back-end stuff than I don't even know exists.
I'm not saying Apple is perfect, but implying they're using an Embrace and Extend style of business is just wrong. Add the extra E (Embrace, Extend, Extinguish), and that's a Google/Microsoft/Facebook way of doing things (and why 1/2 of the fediverse is afraid of Meta actually federating Threads).
[Edit] One last point. Apple doesn't have a proprietary IMAP push mechanism. It uses bog standard
IMAP IDLE, but on iOS and iPadOS only allows it for the single primary iCloud account email address (supposedly to prohibit potentially unlimited network resource usage, which I would agree and argue is probably no longer a concern and should probably be allowed for all IMAP accounts). On macOS's Mail.app, any IMAP account can use IMAP IDLE for push email.