From Android Police.
Many companies reserve certain features for use only within their compatible product range (looks at Samsung for their gatekeeping of Galaxy Watch features to Samsung phones only; heck even TWS manufacturers sometimes bake a feature or two exclusively for use with their phone series only). I wonder if Oneplus offerings are completely platform agnostic or not.
Unfortunately, OnePlus began to lock their Phones with OnePlus 7 and latest Android versions. It was very hard to install LineageOS under these circumstances.
Stay away from them is my recommendation now.
I bought a OnePlus Watch as a gift for someone because it has feature parity across all smartphones. Looked at the Galaxy Watch first and noped the fuck out because of the Samsung exclusive features. Idk why manufacturers do that because they are losing potential customers.