Raspberries are basically for DIY projects. I have one on my router handling call blocking for my landline. If it was costing $300 I would rather get a mini PC or use one of my defunct phones with UserLand on it. I can't see any world where a comparison to an entry level laptop makes sense.

You don't need a $300 pi for call blocking. They still make and sell $30 models that will be an overkill for your use case.