Do you still use Microsoft 365 on Linux, or is there a good alternative?

Microsoft 365 works in a browser on Linux, which is handy if your workplace uses it for shared files and apps. The web apps may be enough for ordinary documents and spreadsheets, though they don't cover every advanced desktop feature.

Browser experience can vary too. Firefox works for some people, but others report problems with it.

Give LibreOffice a try if you want a desktop suite. It's included with some Linux installations and can open Microsoft Office files. For your own documents it may be all you need.

Test the files you actually exchange with other people, though. Complex layouts, fonts, macros and advanced Excel features can cause trouble when moving between suites.

OnlyOffice is another desktop option, particularly if you exchange DOCX files. It's worth comparing with LibreOffice using a few of your own documents. Some layouts come across better in OnlyOffice, but I wouldn't assume every file will be perfect.

If you mostly need simple documents and sharing, Google Docs and Sheets are browser options too. Collabora is another alternative to look at for web-based collaboration. The best fit depends on who you need to share with, not just which editor you like.

For the full Microsoft desktop apps, there's no native Linux version. If the web apps or alternatives don't handle a particular workbook or layout, running Windows in a virtual machine or dual-booting are options. More setup, sure, but useful when compatibility matters more than convenience.