You can change the email address used for an account as outlined in Change your Apple Account primary email address - Apple Support
Apple recently enabled transferring purchases between accounts, as outlined in Migrate purchases from one Apple Account to another Apple Account - Apple Support and About migrating Apple Account purchases between accounts - Apple Support
However, I have seen many threads where people have had problems doing standard things with those old .me accounts. You can ask Apple but I get the impression that even they don't know how to deal with them.
Refer to this page for Apple Support features ➔ Contact - Official Apple Support
Select from the presented options until you find a solution for your issue, or see if there is a chat or phone call contact method offered lower on the page under “Get more help” (you sometimes have to narrow down the options multiple times before this is shown). If you do not see your issue, keep experimenting with any series of selections until you reach one that offers a chat session or a telephone call and get the representative to redirect you.
This support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple Support - Apple Support Scroll down to “Connect with live support”. If your country is not in the list, go to the “Other countries” entry at the end of the list. Not every country has telephone support, and phone numbers may only work when calling from the same country.
For chat, you can try using the Apple Support App —> https://apps.apple.com/app/apple-support/id1130498044
For chat help with a USA Apple Account —>
https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0998&symptom_id=20198
