In align with the privacy rich features of Orion browser, I would LOOOVE to see an auto delete cookie feature.
While browsing the web, you often visit websites you don't frequent - blogs, news websites, seo riddled junk etc. Most of which are notorious for including large amounts of first party and third party cookies.
Orion could natively support popular extensions like Cookie AutoDelete: https://addons.mozilla.org/en-US/firefox/addon/cookie-autodelete/
When turned on, it will automatically deletes cookies of the websites you just visited, after a configurable <N> seconds, upon closing the tab.
The wait period of <N> seconds is to support the scenario where you might accidentally close a tab and want to go reopen the closed tab.
It will also support whitelisting domains for which cookies will be retained and not auto deleted. This is useful for websites you might frequent, and might want to stay logged in, for example. Whitelisting can be easily done from the website settings menu (gear icon near the address bar).
If possible, it should also differentiate between cookies for root domains and subdomains. For example, in the above extension you can selectively whitelist cookies either for *.google.com, or just for *.accounts.google.com. If you just want to use Gmail for example, you can get away with whitelisting only *.accounts.google.com, and don't have to whitelist the entire *.google.com space, which could include *.analytics.google.com as well, for example.
My current workaround is to disable cookies for all websites by default from the Website settings. And only selectively enable cookies from the gear icon for websites I want to enable cookies for.
The issue with this approach is that a lot of websites straightup refuse to function without cookies enabled. A lot of websites using the Cloudflare "verify you're a human", and you can't get past it without enabling cookies, sometimes it will only work in compatibility mode.
I could never get Gmail to work this way because of the numerous redirects they do while logging in - so now all Google stuff stays in a profile of it's own. 🙃
With this feature, the whole experience makes it so you can seamlessly browse any and all websites (no cookies are blocked), but as you leave those websites, they're automatically cleaned up, leaving no trace in your browser.