For those who want to help with Wine development without contributing code, CodeWeavers host the Wine project and contribute to its development along with their own CrossOver product.
For those who've never heard of it:
CrossOver provides two main services on top of Wine. 1) CrossOver contains a series of hacks that allow some popular programs to run better in the short-term. 2) CrossOver provides a user-friendly shell so that you don’t need to use a terminal and text-based commands to run your Windows software on Mac or Linux.
Released yesterday, CrossOver 18.5 is a pretty huge upgrade as it pulls in the Wine 4.0 release (previously it used Wine 3.14) and also FAudio, the XAudio reimplementation for open platforms developed by Ethan Lee who now works with CodeWeavers. The actual changelog can be found here and the release announcement here.
I can't say I know anyone who uses CrossOver for games, but for software it might come in handy, like with this release adding some support for OneNote 2016 and support for the latest latest release of Office 365. Good to have options though of course and since they support Wine directly it's a good way to help.
They also put up a blog post (where the above quote is from) to help with those confused on the relationship between Wine, CrossOver and Proton.