Pretty sure both Firefox and Microsoft Edge both offer it as an option too.
Orion, too.
And Brave
Firefox's new implementation is subpar. You're better off using an add-on like Sidebery for more features, but you need custom user chrome CSS to hide the horizontal tabs.
Zen is lovely but I actually really miss the little arc window. Didn't realize how much I used it until it was gone. Sticking with Arc for now.
Arc works fine; Orion (Kagi's browser) is like an Arc built on WebKit.
I really don't see many similarities between Orion and Arc but I also didn't use Arc very much because I was pessimistic that it would stay free and consistently updated without annoying monetization features. I didn't expect them to switch to a brand new browser though lol.