Hey @Milind_Patel!
Great questions.
For handling customer password updates, we have options for that on the storefront API Manage customer accounts with the Storefront API
One key factor to keep in mind is that password logins are part of legacy accounts. Our new customer accounts use a passwordless login, so if you’re working with multiple merchants you may need to accommodate both scenarios.
New customer accounts can be managed through the customer account API Customer Account API reference
For working with alternative identity providers on new customer accounts, our documents here outline the steps to implement that and the requirements for providers: https://help.shopify.com/en/manual/customers/customer-accounts/new-customer-accounts/identity-provider
Hope that helps!