Yep, you can claim payment gateway charges as a deductible too.
You can find it in the other debits & credits tab in the tax P&L sheet. All the charges in this tab can be claimed against gains from your trades - STCG, LTCG, or business income (in case of F&O or intraday transactions).
Apportioning the AMC for equity transactions might be difficult. However, if you are accounting for your trades as business income (this won’t be true for cases where one is accounting for trade gains as STCG/LTCG in equities), you will be able to claim this as business expenses.