Isn’t AdGuard just DNS?
It isn’t “just” DNS level blocking, no. They have an adblocker for browsers, too. uBlock is using their filters.
other mobile browsers you don’t have any at all
Some have built-in adblockers (ex: Brave, DDG), others support extensions (ex: Safari, Orion).
Kagi uses its own crawler, right? But yeah, I expect DDG to follow Ecosia’s lead.