This was a fun thought experiment, I know some of these aren't the smartest moves but they would be the most exciting to me.
-Pay all of the Apple employees more in line with how successful the company is (share the wealth more equally).
-Setup an incentive structure that makes finding and fixing software bugs just as rewarding as new features.
-On iOS allow side-loading and third-party app stores world wide. As part of that setup a signatory service just like macOS for developers to have their apps signed through an automated service.
-On macOS revert opening non-signed apps back to how it was, just double click the app and then get a warning to proceed.
-Eliminate the 30% commission on digital in-app sales, and if using Apple payments make the rate competitive with other payment services.
-macOS: Yes, it's time: set it up to directly compete with Windows; anywhere Windows can be installed you can install macOS. This will require providing (gasp) genuine 3rd party support so they can make things like graphics drivers.
-Create official PC standard motherboards in ATX and micro-ATX sizes using Apple Silicon CPUs. The CPUs could be soldered for all I care. Possibly create an Extended-ATX board with two CPU sockets.
-Mac Pro, Mac Studio, MacBook Pros: ditch the soldered SSDs and replace with TWO user-accessible gen5 standard size NVME slots. Heck put 3 or 4 on the Mac Pro. Maybe add a second to the Mini too if it would fit.
-All the other Macs replace with a single NVME slot.
-In macOS bring back separate controls for display and computer sleep.
-Change the OS version numbers to correspond to the year, for example "macOS 2025.1". This would make it so much easier to determine how old the OS you are using is, and incentivize upgrading.
-Find a way to alternately load macOS on iPads.
-Create a 12" convertible MacBook.
-Create what is essentially two Pro Display XDR's merged together for one big wide display. Alternately, redesign the XDR with extremely thin side bezels.
-Create an e-ink home hub wall-mounted display thing, totally customizable to be able to pull in data or views from apps/websites/services that aren't necessarily setup to work with it. Like how the old iWeb could let you create a website using snippets from other websites.
-Make a water-resistant micro size Magic Keyboard with Touch-ID, ideal for HTPC's.
-Vision Pro: make a version that is basically a dumb display, ideal for simply consuming content or gaming.
-Add FaceID to the laptops, iMac, and Apple monitors.
-Physical Apple Stores: add normal checkout registers.
-Setup a more official partnership with ColorWare to offer custom colored devices.
-Redesign the Airpods to have replaceable batteries.