“Open sounds” (which, I assume, refers to continuants) and bilabial sounds aren’t mutually exclusive.
When you pronounce the /w/ at the beginning of “one”, your lips round (purse) and touch each other at the corners, but they don’t form a full closure. So, the oral tract is still open, but the articulators (moving mouth parts) are still touching.
This could be reworded as “the middle of your lips don’t touch each other”, but multiple commenters are correct in that your lips absolutely do touch each other when you say “one” in English.
“Open sounds” (which, I assume, refers to continuants) and bilabial sounds aren’t mutually exclusive.
When you pronounce the /w/ at the beginning of “one”, your lips round (purse) and touch each other at the corners, but they don’t form a full closure. So, the oral tract is still open, but the articulators (moving mouth parts) are still touching.
This could be reworded as “the middle of your lips don’t touch each other”, but multiple commenters are correct in that your lips absolutely do touch each other when you say “one” in English.