On Duolingo and Google Translate the pronunciation of ę is like an open ɛ sound.
Needs more research... Native speakers, please help with your knowledge intuition :)
Word-final -ę can be pronounced as either /ɛ/ or /ɛɰ̃/, the former is the usual pronunciation, the latter is used to disambiguate in the situations when the difference would matter.
The forvo recordings sound hypercorrect and even a bit pretentious.
Mid-word ę is pronounced as /ɛ/, /ɛn/, /ɛŋ/, /ɛɲ/, /ɛɳ/, /ɛm/, or /ɛɰ̃/, depending on the following consonant.
ę is never pronounced /ɛu/.