The very basic functionality of task and to-do lists was included in the very first Personal Information Managers (PIM) from the 1990s, and was a primary motivation for the adoption of these sorts of software (and hardware) products -- motivated users were tired of a stack of paper scraps and post-it notes in their purse or wallet or written upon their forearm.

While pleased to see Proton moving to effectively compete with Google Workspace and all the related products, the absence of this very basic functionality makes for a product that cannot effectively replace the sorts of enterprise business systems you wish to compete with -- not to mention significantly hampers the existing user base, as they are compelled to utilize other software, revert to sticky notes on a monitor, or just never adopt Proton at all.

There are other requests over many years for this exact functionality. Respectively, please heed the hints coming from your user base!