This is possible.
in your TinyMCE plugins folder, look for the codesample folder. in this you will fine plugin.js
find line 1101, it displays the languages.
i have updated my to be this....
var languages = [
{text: 'C', value: 'c' },
{text: 'C#', value: 'csharp' },
{text: 'C++', value: 'cpp' },
{text: 'CSS', value: 'css' },
{text: 'F#', value: 'fsharp' },
{text: 'Java', value: 'java'},
{text: 'HTML/XML', value: 'markup'},
{text: 'JavaScript', value: 'javascript' },
{text: 'Json', value: 'json' },
{text: 'LESS', value: 'less' },
{text: 'PHP', value: 'php'},
{text: 'Python', value: 'python'},
{text: 'Ruby', value: 'ruby'},
{text: 'SASS', value: 'scss' },
{text: 'SQL', value: 'sql' },
{text: 'TypeScript', value: 'typescript' }
];
save and then re-minify the file.
then in TinyMCE you will get the new languages in the dropdown, just ensure yoru Prism file is updated to have these languages.