hansmade Orbot works fine on ios but I haven't managed to get Vanadium to connect to my node with Grapheneos.
Are you using Orbot as a VPN, or have you left it as the default proxy? If you want to use Vanadium, you should use the VPN option, though you might want to make some changes to your configuration, like use a different route for each endpoint and only use Orbot for certain apps.
If you do set up Orbot to only tunnel some apps' traffic, you might want to update your VPN settings here: Settings > Network & internet > VPN > *the gear next to Orbot* > Block connections without VPN. Turn that off, OR just remember that you will need to remove the VPN configuration after you finish using it, otherwise your apps will not be able to connect to the Internet.
Or even better yet, just use a dedicated user profile for this and keep the block all connections without VPN toggle on.
hansmade should I try a different browser?
The Tor Browser is probably better for this. It would save you a lot of hassle, I think, if you just plan on using a browser to connect.