Um, well, it’s not as simple as just “let’s sprinkle a pack on it”.
The use case implies that each user has a private space to enter their information. This means each user will need a separate doc created just for them. Besides, since we also need to limit what rows get exposed to that user, this is also only achievable if the user gets their own doc where only permitted rows are synced.
Assuming you’re okay with duplicating some template doc for each user (you can automate the process through Coda API / Admin Pack), indeed my Cross-doc Plus pack should make it easier to programmatically share selected rows with selected user docs through a password system basically. Each doc would have a unique password and each row on your backend tables would have the rule allowing access to docs with this or that password.