The threshold issue here is: "What do you mean by ’jazz’ "? Ellington, Mahavishnu, Wynton, Alice Coltrane, Keith Jarrett, Sun Ra, Sinatra? And are you including boots?
But here’s my two bits: In the 1970s & 1980s, I collected a lot of mind-bending "Rock in Opposition" music that combined jazz, classical chamber music, electronics, and sometimes even heavy metal. Lots of Chick, Zappa, even Yes influences. I also traded Western CDs, with penpals in the Soviet Union and Eastern Europe, for some more conventional jazz records by world-class artists who are little-known here.
I can make a few recommendations. A good first stop would be Komeda’s "Astigmatic," which -- and this is admittedly a poor analogy -- is something like Eastern Europe’s "Bitches Brew." Tomasz Stanko is no Miles, but still great. It’s on Tidal, & you Google Komeda for context. Like Miles, he used to collect young talented players and guide them to become great bandleaders in their own right (when he wasn’t recording soundtracks for movies like "Rosemary’s Baby").
A good place to start for the RiO releases is with the bands Art Zoyd, Univers Zero, and Zao (the French band with Yochk’o Seffer & album "Z=7L" -- there are a lot of Zao’s). Their albums are extraordinarily diverse and often experimental, but you may hear echoes of Weather Report & Pere Ubu. Again, you can find a smattering of these artists’ huge catalogs on Tidal. Another option is Cuneiform’s glorious sampler album "Enneade", which is also on Tidal (Youchk’o’s "Freya" track is pretty hot!)
This is a whole world of jazz that is generally unknown to Americans and most younger Europeans.
Oh, and there are East Europeans who have released a only few albums here, but who have huge catalogs of great records that never made it to our shores. YouTube is sometimes the best (mid-fi) way to sample such artists, like Michael Urbaniak and Iva Bittova (the "Polish Laurie Anderson"!). I see a newly remastered version of Urbaniak’s fusion-y "Inactin" is on Tidal.
I am a huge fan of Rock in Opposition (also known as "avant-prog’), and even though many bands use a fair amount of improvisation, I would not include most of them in any jazz subgenre. But of course, with all attempts to put different bands in genres, the lines are fuzzy.
It seems to me, that (evidenced by the majority of posts on this thread), most people that are into jazz on this forum, tend to not be into anything: recent or that may border on avant-garde. So asking them to venture into: atonal, very complex, angular sounding, "difficult" music may be a hard ask.
For your benefit, avant-prog (Rock in Opposition), did not really stop in the 70’s, 80’s. Along with all other subgenres of prog, there has been a constant supply of avant-prog bands since the mid 90’s. Some incredible music from the recent past, and present.
Check out (this is just a very few):
Thinking Plague - In Extremis (1998), A History of Madness (2004)
Sleepytime Gorilla Museum - Grand Opening and Closing (2001), Of Natural History (2004) They’re touring the US right now!
Aranis - Made in Belgium (2012), Made in Belgium II (2014)
Yugen - Iridule (2010), Death by Water (2016)
Discus - ...tot Licht (2003)
Zevious - Passing Through the Wall (2013)
miRthkon - Snack(s) (2013), Vehicle (2006)
Thank you for this thread! I am from Sweden, started to listen to jazz 3 years ago ( at the age of 70! ) and I love it. It is good to get recommendations.