Technically they’re “downcyclable”. The materials can be separated and used for other purposes, but they’re not “cycled” back into being another tetrapak.
It’s also a very energy intensive procedure so even if it’s possible to use some of the materials again, it’s by no means as environmentally friendly as products that can be recycled for their purpose. Take for instance glass bottles and aluminium cans, they can both be recycled into glass bottles and aluminium cans.
Some places also reuse glass bottles by cleaning them. This also costs energy, but not as much as grinding it down and heating it to produce new glass.
Aluminium cans are probably the best single use beverage container as of now.
The best one is not to get one in the first place. Reduce, reuse, recycle, reclaim.
Tetrapak is in the “reclaim”.
Carrying a personal reusable water bottle is a good idea, because it reduces the production of singular use containers.
Aluminium is fine for acidic beverages and it is possible to buy juice in a can, but that would be a single serving. Juice and milk make sense to buy in larger sizes for multiple servings. Plastic bottles are also an option for those, but it really depends on how they’re recycled locally if that makes more sense than the cartons.
The aluminium red solo cups ought to be recyclable just as any other aluminium product, provided that they’re returned in the first place and not mixed with other disposable garbage. Selling them as disposable seems counterproductive. A better option would be to use actual cups or glasses for picnics and bring them back home. Washing a cup in a dishwasher is much better than recycling aluminium.
It’s not easy for consumers to make a good choice.