There's webkit too by Apple. And browsers based on it is available for Linux too. And no, webkit and Blink are not the same engine. Blink is a fork of webkit by Google and while they share a heritage they have different feature set now.
Also worth noting how different the different goals/approaches differ between the WebKit and Blink teams. The WebKit team is very deliberate in their development, only committing to new features once they have some level of assurance that it can be done with minimal negative impact to efficiency, privacy, and user control where the Blink team moves almost entirely in interest of getting as many new features out as quickly as possible with comparatively little regard to negative side effects.
Both approaches are needed to maintain a balance and to preserve real choice for users — there is no practical difference between Chrome, MS Edge, and Brave because their differences are skin-deep at best.
I was thinking of webkit too, but I'm not aware of any browsers expect Safari and the Linux browsers you mention. Neither seem to be cross platform or practical, "viable" alternatives to Blink domination.
I'd say the scenario is similar to Firefox/Gecko and Chrome/Blink. Sure there are clones that use the Gecko and Blink engines, but none of these really are as popular as their original.
I am waiting for another Opera / Presto browser platform to emerge. Till it did, the browser market dominated by Internet Explorer was literally stagnant. Opera with a Presto engine was a game changer with their light-weight and super fast browser engine with feature sets that all other browsers copied (and still lack even today).
I miss the plain UI speed of Presto-based Opera. I could cycle between tabs at my keyboard repeat speed - now my PCs are an order of magnitude faster and can't manage more than a couple tabs per second if I hold ctrl+tab.
When I do it I can see the URL cycling at my keyboard repeat speed (~30 fps), but the selected tab and page displayed in the foreground refresh about an order of magnitude more slowly. (1-5 fps) (So with a dozen tabs open, the effect is to select/show tabs in essentially a random order.)
edit: FF cycles smoothly (although with a weird white strobing effect with the main blank content area) if I open a bunch of blank tabs, but not if they're actual web pages.
