After some extensive digging in the well functioning dictionary classes I found the UmbracoCultureDictionary library that contains useful stuff like this
new umbraco.MacroEngines.UmbracoCultureDictionary().Language.id
Currently obsoleted and the referenced class Umbraco.Web.Dictionary.DefaultCultureDictionary is Internal, hence the following approach is probably the most compatible at the moment
umbraco.cms.businesslogic.language.Language.GetByCultureCode(
System.Threading.Thread.CurrentThread.CurrentUICulture.Name
).id
umbraco.cms.businesslogic.language.Language.GetByCultureCode(
System.Threading.Thread.CurrentThread.CurrentUICulture.Name
).FriendlyName
umbraco.cms.businesslogic.language.Language.GetByCultureCode(
System.Threading.Thread.CurrentThread.CurrentUICulture.Name
).CultureAlias