Yes, many Windows-based NLE's do permit access to whatever compatible third-party WFW codecs are residing on the system, but for export this usually this requires modifying the profile of an existing system-supported AVI codec to access the listing, configuring the chosen third-party codec and saving it as a custom profile.
Take Vegas for example. If you export to Sony YUV (native codec) the pass-through luminance range of the imported source is preserved. However, if you 'customize' the Sony YUV profile to use UTVideo or MagicYUV instead and configure for 8-bit YUV (YV12,YUY2) encoding, the luma range of the export gets compressed (i.e. full range YUV 0-255 > 16-235). Fortunately with MagicYUV there is 'full luma' option that will counter that, but not with UTVideo. Point being that you cannot assume third-party VFW codecs will behave in the same manner as system-integrated codecs and it pays to examine their behavior in any given system to avoid undesirable outcomes.
In light of that, is that what you envisage by 'WFW support' in Resolve ? Obviously there's a big difference between that and adding system-integrated (native) support for select AVI codecs, especially when support already exists for the Quicktime (MOV) variant, as is the case with GV HQ/HQX.
For one thing the freely available GV (Canopus) HQX codec does not expose the 10-bit variant as an encode option when accessed as a 'standalone' VFW codec outside of Edius, even though webpage information would suggest otherwise:
https://www.grassvalley.com/products/hqx_codec/I do agree though it would be nice to have lossless AVI option's besides Uncompressed.