Thanks for the your reply and the suggestion to use open source apps! We're aware of OpenOffice and LibreOffice.
Despite the desire to refrain from using Microsoft Office 365 and Google Docs, they dominate the market and are often necessary. OpenOffice and LibreOffice are very good, however they do not always render every document's pages 100% identical to what the Microsoft 365 apps render, there are sometimes significant visual or layout rendering differences. More complex documents with intricate formatting, embedded objects, or specific styles are more likely to exhibit differences. While both suites support common formats like DOCX and ODT, there can be subtle differences in how they interpret and render these formats. Updates to either LibreOffice, OpenOffice, or Microsoft 365 can introduce changes that may affect compatibility and rendering. Certain features, such as advanced layout options, graphics manipulation, or equation editing, might have slightly different implementations in each suite.
To be 100% sure of seeing the same rendered pages as the Office 365 users with whom we are collaborating on documents, we very often choose to use the 100% free Microsoft 365 web apps, to eliminate the possibility of unknown and unseen rendering differences between a M365 app and its open source alternative app. For this reason, we need Thunderbird itself (or an extension) to be able to take documents attached to Thunderbird emails, and with one click, button, or keystroke, automatically and smoothly open them in the relevant free, web browser based, Microsoft 365 app. This action - opening an attached office doc in the free web M365 - may be repeated 50 times per day, so it must require just one action input from the users - a click, or a keystroke - and occur automatically from that point.
