ofc it wasnt in same league. it is 13 years older. that's a lot of time for tech in end of 20th
https://en.wikipedia.org/wiki/Grumman_X-29
vector trust 1990
https://en.wikipedia.org/wiki/Rockwell-MBB_X-31
"PROTOTYPE STAGE" was the key word .... ofc the X-29 was great, but the Berkut was something higher (well it was also a prototype but .... i was closer to a functional fighter if it entered mass production) and the only thing they have in common is the FSW and it's not even the X-29 who featured a FSW first
Belyayev Babochka (1939 prototype)
Belyayev DB-LK (1939, first flight 1940 1 prototype also)
https://en.wikipedia.org/wiki/Belyayev_DB-LK
technically the 1st "successful" fighter used in war was the
Nakajima Ki-43 Hayabusa (1941)
https://en.wikipedia.org/wiki/Nakajima_Ki-43 althought the FSW profile was barely noticeable
Junker Ju 287
https://en.wikipedia.org/wiki/Junkers_Ju_287 (still 2 built just like the X-29 iirc flight tested 23 May 1947)
OKB-1 140
https://en.wikipedia.org/wiki/OKB-1_140 (russian Ju 287 .... so it does not really count if they made it fly
nonetheless a little bigger since the real Ju 287 was the OKB-1 EF 131)
and for the Rockwell X-31 .... that's another piece of kit buuuuuuuutttt... woops prototype and the thruster nozzle errrrr paddle are ... *fails for words* (the F-22 is 2D vectorial, Su-30 MK or Su-57 are 3D )
although interesting (saw a lot of TV reportage from them on Planet+ recently) they look like overexpensives toys (that fails hard when the computer assistance fails
quite shocked of accident report)
first 2D jet vectoring was obviously the Hawker-Siddeley P.1127 Kestrel (1960, meanwhile the US did the Lockheed XV-4 Hummingbird 2 yrs later .... and quite a "beauty" compared to the Kestrel /sarcasme), Hawker-Siddeley Harrier (1967), Yakovlev Yak-38 (1971), VFW VAK 191B (technically a German harrier, 1971)then the Yakovlev Yak-141 (1987, which led to the F-35B Lightning II design) and then the Boeing X-32 JSF ( 2000, the unfortunate X-35 concurrent) actually the F-35B derivated from Convair/General-Dynamics Model 200 design (1972, which was only a design, that had a scale model tested in wind tube iirc and lost to the way more unrealistic Rockwell XVF-12 who got 1 flight prototype and was cancelled since unable to hover even with a engine delivering more thrust than his empty weight, 1981 ) tho the airframe is way closer to the Yak-141
3D vectoring ofc there was the F-15 ACTIVE, F-16 VISTA and F-18 HARV but all prototype on the other hand non experimental and entered in active production:
oh and btw i did get these 2 wikipedia pages during my posting you quoted.