On the income statement and balance sheet screen, I would love to be able to quickly filter the list of accounts on Fava to a subset that I care about. It seems that there is only the ability to filter by postings. Am I missing the ability to filter accounts based on name or metadata or is this not yet a supported feature?
Not possible AFAIK. You can filter entries by an account name, but on those screens, it will show all the accounts in the resulting entries. From Fava help:
Filter entries by account, matching any entry this account is part of. The filter can be an account name, either the full account name or a component of the account name, or a regular expression matching the account name, e.g. .*Company.* to filter for all that contain Company.