Captive Portal for Public WiFi (WAG Use Case)

Hi there
Willing to know if anyone is redirecting to an external Captive Portal with VyOS.
The use case is for Public WiFi; new subscribers got redirected toward an external Captive Portal, including some metadata such as AP MAC, EU MAC, SSID, etc.
AFAIK there is no native support on VyOS just looking for workaround ideas.