As a small business owner using Proton for mail, calendar, Drive and meetings, the one thing I still need a separate (paid) tool for is signing contracts.

It would be great to have privacy-first electronic signatures built directly into Proton Drive and Proton Docs:

Send a document from Drive/Docs for signature to one or more people (Proton users and external recipients)
Support for the different signature levels under EU eIDAS and Swiss ZertES: simple (SES), advanced (AES) and ideally qualified electronic signatures (QES), e.g. through a partnership with a qualified trust service provider
Signed documents with an audit trail stored end-to-end encrypted in Drive
Included in Proton Business / Workspace plans, possibly with a monthly quota for QES

Why this fits Proton: Contracts are some of the most sensitive documents a business handles, yet most e-signature providers are not end-to-end encrypted and many are based outside Europe. A Proton signing feature would let businesses keep their entire workflow, from the first email to the signed contract, in one private, European ecosystem.