Bitquery has APIs to get balances and balance updates on Stellar. Check: ide.bitquery.io/latest-balance-of-stellar-wallethttps://ide.bitquery.io/latest-balance-of-stellar-wallet
More examples here: https://docs.bitquery.io/v1/docs/category/stellar
You can sign up for a free developer account at https://ide.bitquery.io/.
Full disclosure: I work at Bitquery
