Carlos-Anso I am not sure what you consider "the desktop equivalent"
VMs.
You are attempting to replicate a somewhat complex setup in another OS, there are big differences as to how things work in these operating systems, and nobody has created something that provides what you want.
The way networking, profiles and VPNs work in Android may appear a bit strange when compared to what you are familiar with from desktop operating systems
I use a different Android variant where this is already possible, so I'm not sure what 'complex setup' is in reference to, but nesting is pressing one toggle in the main profile and then connect in the sub profile's VPN. Just like on desktop. You can definitely get more elaborate in a desktop environment but it's not necessary.
I would not call it a hack or presume that an app designed just for running a VPN would be higher quality.
That's fine. I would. It's true that there are many poor VPN apps but the solution is higher quality apps, not third-party apps that are really 'and we support VPN functionality'. With the increasing captcha-blasting, outright blocking, and AI-powered analysis of more privacy-respecting VPN use, I cannot depend on a team that does not have the VPN and its continued improvement as their primary focus, critical to their bottom line. It's definitely off the table when their real focus has the capacity to introduce bugs that subtly break the VPN. This is no different from how I wouldn't depend on a VPN for ad blocking features that are secondary.
Its technically possible to have networking from any given profile run through nested VPNs. Any VPN company could make their VPN app support this kind of nesting.
An independent project could make an app that sits in the VPN slot and offers this nesting and likely also the location switching and other features you desire.
There are existing apps and methods that can achieve nesting of network connections.
This is mixing things up and contradictory. What is being talked about here is an option to share the Owner's profile connection with a sub profile, not yet another third-party app that handles assumed-to-be extractable configurations of yet two other VPNs.
VPN companies don't need to add any feature for this because they already do support nesting by design. There's no special sauce needed. It's not something the app makes an effort to 'support', it's something the OS itself makes an effort to restrict. The inability to nest profiled VPNs on Android is a uniquely Google introduction. Not even ChromeOS has this restriction as far as I can tell.
So unless you're covering up some secret god-mode app or setting that can pierce through the private space or profile boundary, or suggesting I root an installation Graphene, this is an OS problem thanks to Google, not a user-space app concern.
It appears your imagined ideal is a device wide VPN but also being able to run VPN apps in individual profiles with any VPN connections also nested/routed through the device wide VPN
An option for this in relation to the private space, or profiles more generally, yes. In a similar fashion to those that, for profiles, allow setting a private DNS, notifications, etc. or, locally, allow blocking connections without a VPN, having the VPN always on.
I am not at all sure GrapheneOS will ever take on the work to implement and maintain this.
Yes, which is why I was holding out hope that Google didn't bungle the private space like they did profiles in this matter, forcing downstream forks to have to work to fix it. Unfortunately, no such luck.
I think it may be wise to split this conversation off to a new thread as its veered significantly off topic.
I guess, though I'm not sure what would be the point because I've only really been answering questions about my earlier answer and, as you've said, that's unlikely to bear fruit in terms of being implemented. I did ask for it here in the hope that since it isn't fully baked, it may be easier to fix but that's a long shot. There's also this more general thread but same thing.