Keeping this in consideration, is there a Rose Gold Series 3 Apple Watch?
No. There are regular gold colors but no Rose gold.
Beside above, is Apple Watch Series 3 still supported? Apple Watch Series 3 support continues for another year with watchOS 8. Apple Watch Series 3 is having a hard time updating to new versions of watchOS 7, but there's good news for customers using the hardware first introduced in 2017. watchOS 8 will run on all Apple Watch models that support watchOS 7.
Beside this, what colors does Apple Watch 3 come in?
Apple Watch Series 3 (GPS + Cellular) will be available in gold, silver or space gray aluminum, or silver or space black stainless steel paired with a variety of bands starting at $399 (US).
Why does my Apple Watch Series 3 not have a red dot?
The red dot indicates the Apple Watch has cellular capabilities. The non-cellular version of the Series 3 does not have the red dot. This is to identify the phone capability. It looks more like a record button than a reminder that a call can be made.