There are two ways to add tabs to tab groups on Safari: via the search bar and via the tile tabs overview. Orion only has the latter option and I feel like the former should be available too. Unsure how this works with vertical tabs on iOS as I don't use them.
Orion
Safari
Would allow users to add tabs to tab groups more easily. Implementation-wise there are two paths: when adding the tab to a tab group via the search bar, go to the previous active or preceding tab in the tab group you're currently using; or to stay on that tab and be moved to the tab group you're moving it to. Safari does the former (preceding). See recording below. I feel this behaviour should be customisable in app settings.