As far as I can see the following applies. You might want to double check with Velux themselves.
Velux Active is the result of a collaboration between Velux and Netatmo. I get the impression the Netatmo portion is a gateway that translates the Velux io-HomeControl interface to a WiFi HomeKit solution. Velux Active does not support IFTTT. Velux Active does also support Google Assistant. Velux Active does not appear to support Amazon Alexa.
As the underlying Velux technology is using io-HomeControl it is in theory possible to link to a Somfy gateway which supports io-HomeControl. Likewise Velux seem to claim they can control some Somfy io-HomeControl blinds.
Therefore it might be possible to use a Somfy Tahoma gateway to talk to the Velux products and link the Tahoma gateway to Smartthings. The Tahoma gateway does support Alexa. There is a Tahoma integration to Smartthings listed in these forums.
I plan to get some Velux windows and way back before Velux Active switched to using Netatmo which supports HomeKit I had considered trying the Tahoma gateway since back then Somfy had indicated they were going to add HomeKit support to their Tahoma gateway. They have since cancelled that intention.
It maybe that a Velux KLF 200 might be required instead of the Netatmo product or might be cheaper for you. The KRF 200 is as far as I can tell an io-HomeControl product and is the Velux remote, since this will work alongside the Netatmo modules it does suggest the Velux system is still using io-HomeControl along with the Netatmo products, hence my belief the Netatmo products are converting this to WiFi and HomeKit.
In case it has not already been mentioned a more complex option would be to link the Netatmo system to Home Assistant and then use MQTT to share it from Home Assistant to Smartthings.