For legacy spreadsheets, you're 100% correct. I'll need to keep a version of Excel around forever. If they price me out of 365 by making me pay for Copilot shit I don't use or want, a perpetual license to Office 2019 runs about $20 and will do that job for me.
For new work that I might have otherwise done in Excel, there are good options. Collabora works. Libre Office works. Google sheets works. And Grist is quite good, and self-hostable.
For new work that I might have otherwise done in Excel, there are good options. Collabora works. Libre Office works. Google sheets works. And Grist is quite good, and self-hostable.