Desktop bridge apps can request "full access" permission, which effectively evades sandboxing, but those apps are heavily scrutinized on review. In comparison, the Play Store has no manual approval process and an automated malware scanner that's industry-worst according to independent review. ;) Apple does a pretty good job though, and would be my general recommendation for mobile security.

Note that while Android and iOS both have numerous examples of malicious apps in their store, AFAIK, Windows Store does not (though there are definitely ad-ridden nightmares in there). I found their reviews annoyingly onerous for a literally 50-line UWP app with a single function when I tried to submit something.

The biggest benefit of their sandboxing though is not actually the security limitations of what they can access, but how it's installed, and more importantly, uninstalled. UWP apps are one-click remove, and do not leave any lingering garbage in the registry, as they have kind of like a "registry diff" inside their own folder.

Apps like iTunes which are notoriously messy for install and removal I prefer over UWP because it's much easier to purge them safely.

I still find it a shame that Microsoft didn't get to succeed with Windows Mobile. Now instead of "everyone having one phone" we have "everyone having two types of phones" essentially. I love what Apple does because it makes them profitable, even down to their app store. Any competitor that arises needs to mimic that to remain profitable, I would prefer something where the main things are proprietary but as long as the company's only focus is making a phone OS and not an advertisement platform.

I also find it a shame that Canonical instead of redoing the Desktop Environment for Ubuntu didn't invest that effort into just Ubuntu Mobile (or whatever it was called) and lastly, Mozilla almost had a reasonable thing, they really should of produced a Chromebook competitor first though. I yearn for a sane ChromeOS alternative that's fully open source and runs Firefox by default.

In a parallel universe Microsoft and Canonical team up to make a sane Android competitor that overtakes the market, and build the first Linux distro to be able to run Windows applications in a sane sandboxed environment.