The last time I tried it, which is now a few years ago, LibreOffice Calc was substantially slower than Excell for larger spreadsheets. Like a difference between night and day, it was no acceptable substitute if productivity was a concern, which it usually is.
Imo a big swoop change like this, which is done for ideological reasons, but without practical considerations, is doomed to fail and leave a lasting bad impression in peoples’ minds. Imo it would have been far better to only drop windows 10/11 for a familiar looking Linux distro, while continuing to use Microsoft Office.