Yes I still have the BMW lowered seat and it fits the 2019 C650GT I have.
I have not been on the site for a while & just by chance checked today! The lowered sea is now taking up shelf space in my garage & since I moved into a smaller house, shelf space is valuable. Ha! I was going to sell the 2019 C650GT and put the original heated seat back on. I am holding off selling the bike because I like the bike so much and there are no decent replacements for it in the USA market (not like Europe for scooters Yamaha has a scooter over there with cruise control!). The lowered seat is from BMW and does lower the seating for the driver aprox an inch and I did notice the difference. It did not matter to me that it doesn't have heat (now live in AZ but been riding Bikes for 55 years and never had a heated seat even in Canada).
If interested let me know.