it seems, that all TMS native controls can only be placed on a TForm.
Is there a way to place native control on e.g. a TPanel or TabControl from FMX?
No this is not possible due to the nature of the FireMonkey framework.
Isn't the TWebBrowser a native control on iOS and Android, which can be embedded
in other controls? Is this a limit of the firemonkey on Mac?
The TWebBrowser is wrapper around the native WebBrowser component on Mac OS X and "supports" placing it on a TabControl, and automatically handles the Tab switching, but this has been implemented only for the TWebBrowser control, as you can see in the source code of the tab control.
procedure TTabControl.WebBrowserReallign(Sender: TObject);
BrowserManager : IFMXWBService;
if TPlatformServices.Current.SupportsPlatformService(IFMXWBService, IInterface(BrowserManager)) then
maybe it will work while using the TEmbeddedControl.
The FM iOS implementation using that way.