Please, please, pleas! Don't reinvent the wheel... Just add .odf client like in nextcloud...

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This is critical to me, and probably to many other users, as we have our small business data on Google Sheets, and what's stopping me from fully moving over.

If there would be a privacy-oriented spreadsheet app that has the mentioned features, I could get multiple organizations to jump on the whole Proton suite as enterprise customers.

I won't be able to convince my friends to ditch google collaborative editing without a, even somewhat basic, replacement for Google Sheet, it would be truly amazing to get that!

Proton Docs should just be one product with the ability to open any MS office document and LibreOffice document.

And please add an API too - I would love to use a microcontroller for measurements and send it to Proton Sheet. Currently I need to use Google Spreadsheets for this.

I think spreadsheets are available in Standard Note which is part of Proton world now. Maybe it'll be integrated in Drive later.

As a business user sheet would be a very nice feature to switch away from google.

Yes, spreadsheets would be tremendously useful, and would entice me away from Google Drive altogether, I think. (I bet it's on the cards.....) 🙏

I need it to stop using Google

Like NVR3JCT, Google sheets (and docs) are the last reason I have to stay with google.
I have dozens of small sheets for quick calculations and can edit them reasonably well on mobile and desktop. That is an indespensable feature for me. Cryptpad offers a hole spreadsheet app that looks extensive in functionality, but is unusable on mobile. To be able to quickly input numbers into a spreadsheet when on the go seems to be only possible with google sheets, at least not without some form of subscription.
If proton would offer such a spreadsheet editing functionality, I would transfer my google files immediately and get a paid account.

Literally the last thing I need to completely remove myself from the Google ecosystem. Just basic column/row summing would be fine.

We do NEED this. Basic Documents, Spreadsheets & maybe some sort of Slides copy like Google Docs or Microsoft Office are a must if you plan to store your info on a cloud.

I would second Clayton's idea to not just make it like Google Sheets/excel but Make it like Airtable. I have used Airtable for years and the constantly are cutting back on access and features and make their payment models ridiculous. I think Proton would get a lot of business from Airtable like features.
Doublely better if you can make a Spreadsheet and Database toggle when setting up a Table, but that might be too much.

I hope this becomes a thing especially with the partnership with Standard Notes. They have a spreadsheet functionality already.

A spreadsheet editor with database features similar to Airtable