User → Tor → proxy → Internet? In a leak free (proxy always used) way? In theory, yes. By wretching a ProxyBOX between the AndroidVM and Whonix-Gateway.
Concept in theory:
In practice: Unsupported.
See also:
You could also use android proxy settings - but if these will really use the proxy for everything or not - I haven’t checked. If I seriously needed this and wanted it to be leak-free (reasonably certain the proxy will be used), I’d create a
ProxyBOX.