I need access to Lightspeed Retail

This would seem to be a better question for the Ligthspeed Retail blog.  Only spending a few minutes on their site.   I found 

https://www.lightspeedhq.com/pos/retail/integrations/

Once you determine their integration capabilities..  Then you could use the Ninox REST API to sync the desired data points. 
https://ninoxdb.de/en/manual/api/rest

 Hmm.. That said.. a POS written on top of NinoxDB would be an interesting challenge... :) 

OK.. I trolled around the Lightspeed Retail site and found these links. 

https://retail-support.lightspeedhq.com/hc/en-us/articles/229129268-Understanding-the-API

https://developers.lightspeedhq.com/retail/introduction/introduction/

Lightspeed ofers a full RESTful API..  My recommendation would be to use that..    From within Ninox.. use the "do sever" and the http commands.   Following is a snippet from the Webinar 26_API_get_databases.