Let's consider cars (or vehicles in general) as another mainstream example of completely vertically integrated products which comprise hardware and – now – software.
Toyota Motor Corp., Volkswagen Group (multiple brands), Hyundai Motor Group, GM and Stellantis N.V. are the top 5 largest automakers in the world whose annual output is comparable with that of largest smartphone makers, including Apple (with the adjustment of the scale).
None of the automakers allow anyone outside the vertical(s) they have built to gain a foothold in the verticals. This includes: replacement parts, mandated regular service at an official, brand-certified dealership as the condition of the warranty (for new vehicles), software updates only from the vehicle manufacturer, probably something else. No outsiders are allowed under any circumstances – if one misses a regular service at an official dealership before the warranty period has lapsed, the warranty is automatically voided. Some even extend to chipped/cracked windshields that, if replaced, will void the vehicle warranty, even though there is nothing special about a windshield today.
Vehicle manufacturers are by all definitions stagegate keepers, and they impose expensive services upon their product users without giving them an alternative.
Why are governments allowing this to happen?[0]
[0] I know that it is because of safety regulations as the manufacturer will claim that they can only guarantee the safety of its own vehicle if it has original parts, but let's pretend for a moment that it is not an issue.