FZitadel login flow is based on the OIDC flow, a oidc flow always starts in an application with an authorization requests, which also tells Zitadel where to redirect after the login
FIf no redirect url is present, the user will be redirected to the default redirect url provided in the instance settings. but i guess for your flow that would not work.
Fyes if i understand correct that should work. so in the end there is always an oidc flow.