The evidence is that they talk about having too few Linux devs while not posting open positions for Linux devs. Plenty of Linux devs would be interested in working for them. I would absolutely be interested in working for Proton, for example. They just don't have any genuine interest. Understandably so because of how small the Linux market share is. But let's not lie to ourselves. I like Proton and will probably continue to pay for it for the foreseeable future, but I'm not going to delude myself into thinking they have any interest in Linux at all.