How can I avoid breaking links to DispForm.aspx (i.e. redirect to power app), using modern tools?

Question

I'm replacing some sharepoint custom pages and workflow, and for the sake of this question, assume that there are links to xyz.sharepoint.com/sites/someSite/Lists/SomeList/DispForm.aspx?ID=X that are already out in the wild and people will continue to click them after my new version is released. The "ID" in the links is still going to be useful in the replacement app, so I want to be able to redirect from DispForm.aspx to the next thing. I know I can do that easily with some javascript, if I can get it to load with that page. I'm trying to avoid learning any more about old/doomed sharepoint tech than I absolutely have to.

I thought SPFx would probably do it, so I've been trying that, but it's not working yet. Is there a type of SPFx extension that will allow me to customize what happens when users load that page? Or would I have to modify the DispForm.aspx using the old style tools, in order to insert some javascript and do a redirect from "Old URL"?ID=X to "New URL"?ID=x?

I've played with "Application Customizer" and "Form Customizer" SPFx application extensions.Maybe I'm just doing it wrong, or maybe it just isn't built to run on pages like the DispForm.aspx?

Feel free to suggest a significantly different approach.

Answer 1

I figured it out.

If the List settings have the list experience set to "Classic" (which seems normal for that older type of sharepoint situation), then an SPFx extension will not load.

If the List settings changed to "new experience" then the SPFx can be loaded.

So, in the unmodified pre-existing scenario, the SPFx would not load (and there was no redirect), because it uses the classic experience. When the new application is released, part of the release process will just have to be to install the SPFx with the redirect, and then change the list settings to use the new experience - No SharePoint Designer required.