Learn French: N'importe qui peut chanter, ne serait-ce que pour s'amuser.

Ne serait-ce que is a fixed, invariable phrase meaning "if only" or "even if it is just". It literally translates to "would it not be but". Even if the subject being discussed is plural or feminine, this expression remains exactly the same. Here, it introduces the minimum condition for singing: just for fun.

Why use N'importe qui instead of Quelqu'un or Tout le monde for "anyone"?

N'importe qui emphasizes the lack of restriction, literally meaning "no matter who". Quelqu'un means "someone", which does not capture the "anyone at all" vibe. Tout le monde means "everyone". When you want to say "any random person", n'importe qui is the exact phrase you need.

Why is s'amuser used in the infinitive here?

In French, prepositions like pour, sans, or de are directly followed by a verb in its infinitive form. Here, pour translates to "in order to", so it is immediately followed by the reflexive infinitive s'amuser (to have fun / to amuse oneself).

Can I use ne serait-ce que before things other than pour plus an infinitive?

Yes! While it is followed by pour s'amuser in this sentence, ne serait-ce que can also directly precede a noun or a pronoun. For example, you could say ...ne serait-ce qu'une chanson (...if only one song) or ...ne serait-ce que toi (...if only you).