We are in the process to modernize all our Classic Sites to Modern Sites. We are re-creating all the sites and migrating the content from the older (classic) site to a newer (modern) site.
In this process, we are converting the Classic Subsites to Modern Sites.
Users have been provided the navigation links to the content from existing sites. So, we cannot change the URL of any site we are converting to modern. To manage this, we will be swapping the URL for root-level sites so not an issue there.
But, for subsite (e.g. Marketing Subsite inside Sales Site collection - /sites/Sales/Marketing), this is a problem. Because the example subsite here will become root level Modern Site with URL like /sites/SalesMarketing.
Now, anytime any user tries accessing any content with the Navigation URL provided for the Marketing subsite, we need them to auto-redirect to the new Modern subsite.
Please let me know what approach fits best here, any help would be appreciated.