If there were someway to sync Vivaldi with an iOS browser, I'd have already switched. I've really been quite impressed with it, and it seems better every time I check, but I get a lot of use about the cross-device features of Firefox/Chrome, and while that's possible on Android, Vivaldi still don't have an iOS version.
I have around 1000 bookmarks and sync does really help. Since Brave has an iOS version I just use that but I hope someday they will release it.
At least on Linux it gets out of my way quite nicely. Things like easily accessible Profiles help me quite a lot with my workflow.
If you're really strict about privacy there are browsers like ungoogled-chromium, Bromite (Android) and Orion Browser (only on Mac, iOS) which promise 0 telemetry, connections against their services, etc. Brave is nice but has connections against their services (internal addon updates, safe browsing, updates).