DOA does not work with Oracle 21c, because UseOci80 is set incorrectly in TOracleSession.LogOn. UseOci80 is based on the Oracle version string.
In terms of code, there are many ifdefs related to Tibero, but there is no tibero.pas and there are a number of changes from the previous version.
Versions are not maintained in Oracle.pas since 2013. Can we know what are the changes in the Alexandria version? In a production environment it is very risky to use something whose modifications are not documented.
Is is safe to change the lines in Oracle.pas 6420-6427 as You did it in the "Tibero" version for use with Oracle 21c?