They've made HDPE bottles for a while. When I was guiding canoe trips 20 years ago, the wisdom among the guides was that the HDPE ones will float, even if you fully submerge them with the cap off, whereas the Lexan ones will sink.
Aren’t the HDPE Nalgene the original one carried in the 90s, then polycarbonate came out, whoops BPE then transition to Lexan?
I loved the HDPE and appreciated it was likely the most inert (aren’t milk jugs HDPE?), but my family says it imparts a taste so we have a ton of Lexan.