Wait so if your a size 10 UK that's 10.5 US and Heelys doesn't make half sizes. I can't remeber if they did back in the day but they don't now so I would definitely go with size 11 not 10.

They did restock the 20 Pros not too long ago but there out again.

If your into the limited edition Harlem Globetritters they have size 11 on the Heelys site.

https://heelys.com/products/hustle-harlem-globetrotters

Otherwise Amazon has the Pro 20's in size 11 here.

Heelys GR8 Pro 20 Black/White/Red 11 Men's

https://www.amazon.com/dp/B07SK87PQL/ref=cm_sw_r_em_apa_i_1uZAEbB7JVB04

Heelys GR8 Pro 20 Black/Grey 11 Men's

https://www.amazon.com/dp/B07SH7Z9QP/ref=cm_sw_r_em_apa_i_9vZAEbTTSPP16

Then the Heelys Launch there is plenty of color ways in size 11 here on Amazon.

Heelys Men's Launch Skateboarding Shoe, Black/Red, 11 M US

https://www.amazon.com/dp/B01I9Y09AO/ref=cm_sw_r_em_apa_i_SwZAEb9R1M7KE

Heelys Hustle on Amazon with the American Flag in size 11

Heelys Hustle (778102) USA Mens 11.0 / Woms 12.0

https://www.amazon.com/dp/B01LYEYED0/ref=cm_sw_r_em_apa_i_-xZAEb9V5Y5KM

Men's Voyager Size 11 on Amazon.

Heelys Men's Voyager Tennis Shoe, Black/Red, 11 M US

https://www.amazon.com/dp/B07QF9QL9C/ref=cm_sw_r_em_apa_i_tBZAEbMXAJT49

There is plenty of option for you to choose from in size 11 on Amazon. I'm sure there is more but you can look though the pages. But I think I have you lots of options to choose from.