Betta Fish: Would a betta be happy in this tank?

Just looking for advice before I make a decision.

I have a 40g sub tropical tank and brought this 5g as a shrimp tank as I thought my white clouds were picking them off.

Turns out no, shrimp just don't like my water which is hard with a high PH around 7.5-8.

Please excuse the diatoms on the glass, my last and favourite shrimp went a couple of days ago and it needs a water change.

My only options now for a 5g is a betta? Or break it down and sell it to someone who can keep shrimp alive.

But would a betta be happy in this tank?