Micky Mouse Bullet train

Do you think this shinkansen cover by JR nation wide pass and JR Kyushu pass?

No problem, also covered both.
https://www.jrkyushu-wakuwaku.jp/
https://www.jrkyushu-wakuwaku.jp/calendar/

5/17 : only a "Private" train, just also you can see.
5/18 - 19, 21 - 30 : Regular train as "TSUBAME つばめ" or "SAKURA さくら".
5/20 : No operate.
6/1 - : Schedule uploaded yet.

With star mark ones you may buy special goods if not sold out.
https://www.jrkyushu.co.jp/news/__icsFiles/afieldfile/2019/04/23/0012....

No operate on SANYO Shinkansen section, btw Hakata, Kokura and more east(=out of Kyushu region).

Kyushu Shinkansen "Micky Mouse" trains are Sakura or Tsubame trains.
So, yes, they should be covered by Japan Rail Pass.
JR Kyushu Rail Passes
(All Kyushu | Northern Kyushu | Southern Kyushu Area Passes)
cover them inside the validity area.
At the weekends some trains may be packed for specific sections, though.

The operation of the "Micky Mouse" will begin on May 17.
(On May 17, only one train for invited passengers runs.)
Trains scheduled until May 31 mostly go between Hakata and Kumamoto.

JR Kyushu Rail Pass (Fukuoka Wide) is not valid on the Shinkansen.

Sir,your help is highly appreciated.

As other users said on this forum, the Mickey Mouse train is fully available to Japan Rail Pass holders. Source: https://www.jrailpass.com/blog/mickey-mouse-shinkansen

I read on this blog post that as part of Mickey’s 90th-anniversary celebrations, Disney and JR have teamed up to create a specially decorated train which will run on the Island of Kyushu between May and November. The inside of the Shinkansen will be decked out with themed seat covers and a specially decorated interior. Also, there will be available limited-edition merchandise. This Shinkansen for sure will offer a ride like no other.