Functional(), ⁹⁰⁴ 880 bytes

!,",1,#,2,$,3,%,#(1,#(%,$ %($(!,#,")($ 1($ $(% !,% ",% #,% 1,% $,% %,%(%())))))%)" !),#(2,%(!,!,")!),#(3,%(",!,")!),#(4,%(!,")!),#(5,%(",")!),#(0,%()!),#(8,%()"),#(9,% " "),#(<,%(!,")"),$()(9(%()))($ !(#(!,$(1,")(1 ",#(%,$ %($()(%(),"(8,0)()," 9(" 2(" <(1 #)))))%),!)))! 1 < 2 <(1,") < 3 <(2,") < 4 <(3,") < 5 < 3 8(1,") < 3 8 5 < 4 0 5 8 4 8 1 < 3 < 2 9 8 4 0(1,") 8 4 0 4 8 5 0 1 < 5 0 2 < 5 0 3 < 5 0(1,") < 5 0 4 < 5 0 5 < 5 8 5 8 9 9 9 9 9 9 5 9 2 0 1 9 < 3 8(2,") < 5 8 1 < 1 < 2 9 1 9 < 3 8(3,") < 5 8 2 < 1 < 2 9 1 9 < 3 8(4,") < 5 8 1 < 2 9 1 9 < 3 8(5,") < 5 8 2 < 2 9 1 9 < 3 8(0,") < 5 8 9 1 9 < 3 8(8,") < 5 8 9 2 9 < 3 8(9,") < 5 0 2 0 2 9 < 3 8(<,") < 5 8 1 < 2 9 2 9 < 4 8 9 8(9,") 8 5 8 9 9 9 8 4 0 1 8 3 8 1 < 4 8(1,") < 2 9 8(1,") 0 2 < 3 8 5 < 4 0 5 8 4 8 9 8 5 8 9 < 2 8(8,") <(0,") 9 8 9 < 2 0(9,") 8 2 0(2,") 8 2 0(<,") 8(1,") 0 3 9 9 9 9 9 5 9 < 1 9 9 9 1)

Try it online!
Try the 904B version online!

This code comes from a generator code below;

0,1,a,:,b,&,c,>,
:(a,
  :(>,& >(
      &(0,:,1)(& a(
          & &(> 0,> 1,> :,> a,> &,> >,>(>()))
      ))
    )>
  )1 0
),:(b,>(0,0,1)0),:(c,>(1,0,1)0),:(d,>(0,1)0),:(e,>(1,1)0),
:(`,>()0),:(h,>()1),:(i,> 1 1),:(l,>(0,1)1),
&()(
  i(>())
)(
  & 0(
    :(0,&(a,1)(
        a 1,
        :(>,& >(
            &()(
              >(),1(h,`)(),1 i(1 b(1 l(a :)))
            )
          )>
        ),
        0
    ))
  )0
 a l b l(a,1) l c l(b,1) l d l(c,1) l e l
 c h(a,1) l
   c h e l d ` e h
       d h a l c l b i h d `(a,1) h
           d ` d h e ` a l e ` b l e ` c l e `(a,1) l e ` d l e ` e l e h e h i i i
       i i
     i e
   i b ` a
 i l c h(b,1) l e h a l a l b i a i l c h(c,1) l e h b l a l b i a i l c h(d,1) l e h a l b i a i l c h(e,1) l e h b l b i a i l
 c h(`,1) l e h i a i l c h(h,1) l e h i b i l c h(i,1) l e ` b ` b i l c h(l,1) l e h a l b i b i l
 d h i h
  (i,1) h e h i i
 i h
   d ` a h
     c h a l d h(a,1) l b i h
        (a,1) ` b l
         c h e l d ` e h
             d h i h
               e h i l b h(h,1) l(`,1) i h i l b `(i,1) h b `(b,1) h b `(l,1) h(a,1) ` c i i i
             i
             i e
         i l
         a
     i i
   i a
)

Try the generator code online! ( Try the encoder script online! )
Try the 904B generator code online!

The core part of the code is encoded with `,a,b,c,d,e,h,i,l for space,0,1,:,&,>,(,),comma respectively. To output a,b,c,...,etc. themselves, use "(x,1)" format like "(a,1)".

The actual characters in the quine code,

• 0,1,:,&,> are converted to !,",#,$,%
• `,a,b,c,d,e,h,i,l are converted to 0,1,2,3,4,5,8,9,<