Shouldn’t I be able to pass the t variable to an URL to set a dashboards graph timeframe, by just adding ?t=[time in ms] ?
It depends on the context in which you’re viewing the dashboard. If it’s at a Losant address (app.losant.com/dashboards/{dashboardId}) then yes, you should be able to.
If it’s an experience dashboard, it’s up to you do map the request’s “t” query parameter to the time of the dashboard.
If it’s an embedded dashboard, it would require some additional work on the hosting web page to tie the two together.