Can a preprocess hook convert the default ul of hyperlinks into a drop-down select list? Something like this hook.
function THEME_preprocess_links__language_block(&$variables)
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Sign up to join this communityYou can copy the core/modules/system/templates/links.html.twig
into your theme's templates directory, call it links--language-block.html.twig
and in this file adjust the output from the default ul/li structure into a different html structure.
NOTE: there is already 3 maybe more modules that convert the language switcher to dropdown lang_dropdown, dropdown_language and bootstrap_languages.