It looks like the the creator (Jon Sneyers) has since (2019) made another image format more focused on the lossy compression, FUIF[0], which itself has been subsumed by the JPEG XL format[1]. I hope the "JPEG" branding doesn't make folks think that JPEG XL isn't also a lossless format!
JXL is an interesting standard. Integrates a recompressor that shaves ~20% off .jpgs without further loss(!), FUIF for essentially-lossless images in a progressive/interlaced mode like this, a separate lossless format, and a new lossy format with variable-sized DCTs and a bunch of other new tools (other transforms for DCT-unfriendly content, postfilter for DCT artifacts, new colorspace, chroma-from-luma...). It's intended to be royalty-free.
I'm not sure if putting it all under one standard will make it hard to adopt, and/or if AVIF (based on AV1) will just become the new open advanced image format first. Interesting to see in any case.
I think the progressive loading feature of FLIF/FUIF/JXL would be really interesting for WebGL. WebGL games already have asynchronous resource loading and incremental image decoding/texture upload just by virtue of using the available APIs. One could get a pseudo texture streaming effect by default (although no unloading of textures...)
Most of them had expired. Wavelet is something that looks good in theory but in practice couldn't beat the millions man hours work put into standard DCT.
[0] https://github.com/cloudinary/fuif [1] https://jpeg.org/jpegxl/index.html