I'm upgrading a relatively large, but low budget, local government website from Craft 2 to Craft 3. The major remaining pain point is a replacement for the Craft 2 Reroute plugin, which is not available in the Craft 3 Plugin Store.
The main use of Reroute was redirecting existing URLs to other URLs within the site (and against my preferences to external URLs as well). The site is built around a strong hierarchy and quite often the parent page of "section" is redirected to the first child page (because the parent page serves as a conceptual folder and has no content on its own). And because Reroute worked well old entries/pages were not always deleted, just redirected to their new location or replacement pages by the content editors.
In Craft 3 we have Redirect plugin, Retour and Sprout Redirect, but as far as I can tell they only redirect non-existing URLs.
Now I could add a redirect Entry field to the various sections, and manually manage it that way, but it is quite a lot of work in the midst of an upgrade done by one little person (me).
So have I misunderstood that there are no existing plugins that will redirect existing URLs? Or am I missing an obviously easy way of doing this?