混沌 and 葫蘆 are 聯綿詞/連綿詞. They are disyllabic words that the characters are only used to record the sound.
混沌 is originally 天地未開闢以前之元氣狀態 (the chaos before the sky and the earth were separated), and also extended to mean confused. In 《聯綿詞組叢考》, the word family of 混沌 includes 餛飩、糊塗、荒唐、崆峒、倥侗、汪洋、渾淪、鶻淪、昆侖 etc. They are all s0emantically and phonetically related.
葫蘆 is also related to the genesis myth. 闻一多 thinks 伏羲、女媧 (sort of the Chinese Adam and Eve) are phonetically related to 葫蘆. I also found newspaper saying 盤古 (the mythic figure who separated Sky and Earth) is etymologically 葫蘆. Some regional (Han and also other ethnic groups) myths also have it that people escape the Great Flood in 葫蘆. I don't know how credible these views are.
However, I haven't read anything that put 葫蘆 in the word family of 混沌 except for a Yi language (彝語) book. It that says that 葫蘆 is a symbolic for 宇宙混沌 (I couldn't find this mythic view in Han mythology), and that the Chinese words 葫蘆 and 混沌 have the same phonetic and semantic origin (reason is not given). The Yi version of 宇宙、葫蘆、囫圇 are clear semantically, phonetically and graphically related. The Yi and Chinese languages are closely related.
Are 混沌 and 葫蘆 are semantically and phonetically related? Is there any other evidence for or against it?
Inspired by the comments, I found the following.
Many ethnic groups in China, e.g. 彝、拉祜、哈尼、佤, have genesis myths connecting to 葫蘆, but not the Han people, possibly except for the name of 伏羲,女娲 and 盘古. I need to read more about it.
In Han legends, 孟姜女 was born in 葫蘆. It's made up by I-don't-know-who. Linguistically it's incorrect since 孟 means the eldest child, but in the legend 孟 and 姜 refer to two families.
According to the Baidu page, 端午節掛葫蘆 came from 呂洞賓, but he's said to be fro AD 798-880. It's too late for genesis myths. However, 葫蘆 is indeed somewhat sacred in Taoism. There are a lot of 法器 (magic weapon) that are made from 葫蘆.
Another implication of 葫蘆 in Han culture is 多子多福, because 葫蘆 has many seeds. This is similar to 石榴 (pomegranate). 葫蘆 is also phonetically similar to 葫蘆. But this is likely an coincidence since 福、祿 are two words and 葫蘆 was also called 瓠/匏 in ancient times.