Phonetically there is no difference between nous partageons et nous parlons regarding the -eons and -ons endings. It’s like you said. Keep the g soft.

Note that this e is not introduced in all the tenses and persons.

See, e.g. the conjugation of partager.

Nous partageons mais nous partagions (imperfect tense).

Past simple:

je partageai tu partageas il partagea nous partageâmes vous partageâtes

etc.

https://conjugaison.lemonde.fr/conjugaison/premier-groupe/partager/