How to provide a separate SSL certificate to a specific path?

Question

Nginx

Good afternoon. A few years ago I wrote a simple online store on Rails, launched it through Passenger on Nginx-e, set up SSL and enjoyed life :) The
SSL certificate was certified by COMODO. After signing the certificate, I copied it to a server and gave a copy to the bank (on the side of the bank, the Payguide Acquirer system, which requires SSL and the *.crt file itself in order to work with the online store). And now, after the next renewal of the certificate, the bank refuses to accept a new file - they say the format is wrong. As a result, the site itself works, but you can’t buy anything. After comparing the certificates, I found out that only hashing algorithms have changed, which Payguid, apparently, is not designed for.
After negotiations with a bank employee, it turned out that a self-signed certificate can also be used, only I need to send this self-signed certificate along a special path, for example https://example.com/confirm_payment, and for all other requests, give a certificate signed by COMODO.
The question is, how can this be done? SSL is now configured on the Nginx side

Answer 1

Not in a certain way.
You can raise another server on a different port and use your certificate there..