Samsung smartwatch cell phone?

I recently bought a Samsung Galaxy Watch (46mm).

I currently have a Huawei p10 which is now only giving up the spirit why I want to buy a new cell phone (Huawei p30 lite or samsung a50)

So far had no problems with the behavior between mobile phone and smartwatch, but the seller told me that the watch would work better with Samsung devices than with other brands.

How is that true? What are the advantages of a Samsung cell phone?

Well "work better" is always relative it may be that there are some functions that only work with Samsung devices such as an Apple Watch with an Android phone. If the range of functions with your current cell phone was sufficient, I would not make it dependent on which cell phone you buy.

I have a Gear S3 and a OnePlus 6. I haven't found any restrictions because I don't have a Samsung device. Either it was hidden perfectly or there are none.

There might be a Samsung exclusivity for the upcoming Samsung Pay.

The smartwatch at Samsung may have merged into the system a little better. Since you can install all the necessary apps, there are no disadvantages to the non-Samsung device. In connection with an Apple device one would have limitations. But these run back to iOS.