Yes SCRAM-SHA-1 is supported:
https://docwiki.embarcadero.com/RADStudio/Alexandria/en/Connect_to_MongoDB_Database_(FireDAC)
You need to configure the certificates and etc. as indicated in the "Using a Secure Connection" subtopic, this is the easiest part... but then you have this "small" detail:
Note: The MongoDB C driver has been compiled without SSL support. If your application requires SSL, you should compile the MongoDB C driver on your own and provide an additional set of required libraries. These libraries might require the OpenSSL and Microsoft Visual C++ Runtime libraries.
For some reason MongoDB doesn't provide the SSL version from his native C driver (used by Firedac) out of the box. You can find more details here, also the instructions around the driver compilation with SSL enabled:
https://github.com/mongodb/mongo-c-driver