New GS 2031 can be pledged only after it is approved by the Clearing Corporation (CCL) and subsequently included in Zerodha’s approved securities list. There is no fixed timeline from CCL for the approval/inclusion of a newly issued security, so confirmation is not possible at this point.
Regarding the 6.58% yield, this is the indicative yield/expected return for the security and should not be confused with the coupon rate. The actual yield will depend on the price at which the G-Sec is purchased.
We recommend checking Zerodha’s approved securities list using the ISIN once CCL approval is received.