Triangle device that has a heater like an electric kettle. They lay along the long side standing up. Pump rolls/jets hot water over the top down through the straws. A few ridges on the back and a removable filter to rinse in the sink. Could be less than 50 for a stand alone device, a dish washer could build it into the front closing door, just needs the jets for water ran there. The heat would already exist in the dishwasher.
Edit: I do agree it wouldn’t be the perfect cleaner, but a dishwasher isn’t that. Also most straws are pretty similar in diameter. Strange straws would just not go on there, like how strange cups don’t fit in dishwashers.
I think the most common issue with metal straws we will find is people complaining the metal feels cold on their teeth. I never had that issue, but my partner has said it to me before, she uses those rubber tips for the end of the metal straw