The reponse is going balls deep on Foss but I don't think your avg westoid regime is willing to open that Pandora's box.
I mean, GMail is from Google who uses Linux/GNU extensively (as per https://www.computerworld.com/article/1612523/the-story-behind-google-s-in-house-desktop-linux.html and https://news.ycombinator.com/item?id=16175182 )
Even M$ supports using Outlook on Linux/GNU via the webapps (see https://answers.microsoft.com/en-us/msoffice/forum/all/microsoft-365-and-outlook-for-linux/0eeaef13-c337-4c92-8260-8ac7fdf4df9f ) and back in the day they ran Hotmail on FreeBSD ( see https://news.ycombinator.com/item?id=31113296 )
The issue here isn't the use of FOSS per se but that these folks aren't tech savvy and don't want to run things themselves - they'd rather pay someone else to do it. They want "enterprise customer support" and all that. And then whoever they pay might end up bailing out due to fear of US sanctions ... which sadly even Swiss banks aren't immune to.
Either EU can do it now or later
The sooner they stop/prevent/workaround the abuse of power by the US here, the better.
I hear what you're saying. Just remember that Cygnus Solutions and Red Hat, both prominent commercial supporter of FOSS, were based in and headquartered in the US when they were independent companies. (Now they're both part of IBM.)
Even the Linux Foundation and the Free Software Foundation have to obey US sanctions - LF is based in San Francisco and the FSF is based in Boston.
Going FOSS is good, but the US abusing their sanctions powers is a different kettle of fish.