Is it not normal to have an invoice approval process? It amuses me that NS does not have permission-based approval process for invoices or a bulk approval page similar to sales order.

I don't think it makes sense to have one. The Sales Order is when the sale is actually committed, so makes sense for the approval step to involve that

But not all sales have to go through SO especially for certain industries.

What technically is stopping you from creating a SO that goes through approval, then invoicing? Perfectly viable workaround unless you have a reason not to 🙂

Yeah we ended up just using sales orders and the fulfil button even though the ask from our business was for invoices to be held for approval. They're reasonably happy

Thanks everyone. It seems like there's no other choice anyway. Creating a Suitelet is a little bit too much for us if that's even possible to mimic the bulk approval page.