We have found 3 software records in our database eligible for .opt to .myd file format conversion.
MySQL uses many different file types for different purposes and .opt and .myd files are one of these. But not every file type can be converted as these files contain different kind of data, as such opt to myd conversion seems unlikely.
If you have issues with export of MySQL file types, it would be best to contact their support or some online community.
OPT
Files with opt extension are related to the MySQL relational database management system and used for its database data.
MYD
Files with myd extension are used for MySQL database data files that store table row data for MyISAM table. They are also included in MySQL database backups. Content of the myd file can be viewed in MySQL management tools, such as Navicat, EMS SQL Manager, MySQL Workbench etc.