Can one pronounce an ん with closed lips (as in がんばろう)?

Question

I know that when pronouncing the Japanese ん:

1. There should be nasal air flow.
2. You should not be touching your tongue to the roof of your mouth (i.e. so it's not like the English "n").
3. Tongue position is determined in part by the surrounding vowels.

However, consider the word

頑張ろう！

Here there is an ん in between が and ば: がんばろう, so when pronouncing this, I am tempted to

1. Pronounce the が
2. Close my lips, in preparation for saying ば.
3. Pronounce the ん with pure nasal air (since my mouth is closed), and without touching my tongue to my mouth.
4. Move to an open-mouth position while pronouncing the ば (which is easy since my mouth is already closed from (2)).

However, steps (2)-(3) feels like it might not be native, since my mouth is closed while pronouncing the ん. Should I instead be keeping my mouth open while pronouncing the ん here? Or is this not necessarily a mistake?

Answer 1

It doesn't matter. And condition 3 makes condition 2 not necessarily true.