@2ndlight I am using both Zerodha's Coin and Kuvera for investing in mutual funds, from different family members accounts. Both of these platforms are excellent and do the job well.
Zerodha has storage in Demat form, which could mean that in the future you have to pay some small percentage as the redemption charge, but I think the chances of that are very slim. And on the other hand, having to transfer into the wallet for investments and receiving redemptions in the wallet itself makes things simpler. Also, it is easier for the next of kin to claim since their is a single party to claim against. But with a Zerodha account, you also get the ability to apply for IPOs, buy stocks directly, but for this privilege, you have to pay a 200 rupee account opening charge and 300 per annum fee.
On the other hand, Kuvera is basically acting as an aggregator for the mutual funds' websites themselves so there is no fee of any kind and it does the job competently, for both investing and tracking. I can think of no downside honestly, if you just wish to invest in mutual funds only, except if something happens to you, your next of kin will have to make separate claims with each AMC.