Your metal beer cans have a plastic liner in them. Every single one.

Saw a video of someone dissolving the aluminium and it was left with a soft drink in a plastic bag.

Correct, however it is significantly less plastic that would be used in a plastic bottle, since it doesn't have to hold any pressure by itself. The aluminum is one of the most recyclable materials we have.

Klean Kanteen had some drama because they weren't clear on what their liners were made of before they started telling people their products were safe.

Narrator: they weren't

They had to do a big mea culpa and then scramble to change their product line later in the game than they could have.

And then there was an organic food company (Muir) that dragged their feet on switching the liners for their canned tomatoes and sauces (you may recall that acids make the leaching worse) and pissed a lot of people right off.

Silicon as well. If it’s safe enough to have in your body, it’s safe enough to drink from. Also it’s extremely heat resistant (I use it for sous-vide cooking).

Silicone, BTW. (As opposed to the stuff Intel etches.)