Only investing legally with Webull in US Exchange?

I think BTST will be legal right because it is not intraday?

If yes?

Will the BTST be considered in US time zone or Indian time zone?

Example:
If I buy 10 shares of tesla today at 1:29am IST (3:29pm ET) just 2 minutes before market close time in the US (US market closes at 4pm ET)

And If I sell the stock at 7pm IST the same day (that’ll be next day in the US around 9:30am that’s US market opens)

will this be legal?

Here BTST is done in US time zone not in IST time zone

Or should I follow indian timezone?