Hi @Lagertha, and welcome to the Community!
We currently do not have an integration with LightSpeed ecommerce, but I will certainly share this product feature request with our Product Team for further consideration!
Also, If you haven't already, I would suggest taking a look at our Developer portal, especially our Integrate a platform without a pre-built Klaviyo integration Developer Guide. The amount of time and resources required to build out a custom integration vary greatly based on the bandwidth of the developer, the type of integration, etc., so it’s hard to determine how exactly how long it would take.
If you do choose to go down the custom integration path, I would highly suggest that your developer join our Developer User Group here in the Community, where there are over 200 other developers asking and answering questions that your team may also face along the way!
Please let me know if I can clarify anything further and thank you for using the Community!
- Brian