According to The Register, developers can only test third-party web browsers on devices physically located in the EU.
While the iPhone simulator can be used on Mac for initial testing, certain actions can only be observed on a real device. This limitation makes it difficult to identify and fix errors without the ability to install the browser on your iPhone.
In the past, Apple required web browsers for iOS to use the same WebKit engine as Safari. DMA now allows developers to use alternative browser engines; for example, Google may release an iOS version of Chrome with the same engine as its PC counterpart. But stringent testing requirements may deter developers from such “innovations.”
Source: Ferra

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