To ensure that all users see Person Accounts, but only specific users can view Financial Accounts, the Admin should take the following steps:
Grant users access to the Financial Account object with permission set, which is a collection of settings and permissions that give users access to various tools and functions. The Admin can use permission sets to grant access to the Financial Account object and its fields to specific users or groups of users1.
Change Organization-wide Defaults (OWD) sharing on the 'Financial Accounts' object to Private', which is a setting that determines the baseline level of access that users have to records they do not own or share. By setting the OWD sharing on the 'Financial Accounts' object to Private', the Admin can ensure that only the record owners and users above them in the role hierarchy can view the Financial Accounts. Verified Reference: 1

Rollup By Lookup (RBL) summaries are available for the following objects:
Financial Accounts, which are records that represent financial products or services that a client owns or uses1.
Assets and Liabilities, which are records that represent the value of what a client owns or owes1.
Contacts, which are records that represent individuals who are associated with an account3.