Yes, syncing, Addon support (noscript, ublock, "* fingerprint protection" (scrambling specific IDs to make you less unique)), custom search engines, local dark mode (without fingerprintability), local translations are the things keeping me with Mull.
Even though I know Mull may be unsafe, I can use Noscript and by default block all Javascript, but whitelist certain kinds for specific Domains. This is so important and it does not work in Vanadium.
Syncing (history, open tabs, passwords, bookmarks) are also major drawbacks.
For Bookmarks there is Floccus or XBrowserSync but I have not tried them and afaik they dont integrate on Android like a Password manager would do.
For Passwords I could rely on KeepassXC only, but when I find out how to isolate my then favourite browser (hardened Brave?) with bubblewrap, the extension will probably break.
Brave does not have an own Addon store and afaik doesnt even allow updating them. This is a pretty big no for me, as the Addons need updates.
Granular control like with Noscript is not working in Vanadium. Also I could not find out how to delete cookies except from whitelisted sites, which is essential too and even only works on Firefox Android using "ForgetMeNot".
Custom Search engines are completely unavailable, which is really annoying. I like
- random searx
- wikipedia
- an image search engine without the extra click
- thesaurus
- software stores
- ...
Search engines are awesome. Setting a single one as startpage doesnt help, even though one could probably code a website allowing to use many search engines from an input field, and maybe even host it locally from an App.
Brave on Android doesnt do any of those things apart Sync. And its pretty bloated, but works well. I would not trust Vivaldi at all. They arent even doing proper fingerprint protection, and for sure no security hardening.