use feature qw(declared_refs) doesn't seem to make sense without the other feature.

Yes, but the refaliasing does make sense without declared_refs, so it's possible that refaliasing could be accepted without declared_refs.

Upd: Removed incorrect claim once present here. Bad test.

$ perl -M5.022 -e'
   my $x = 123; \my $y = \$x; say $y;
'
Experimental aliasing via reference not enabled at -e line 2.

$ perl -M5.022 -e'
   use feature qw( refaliasing );
   my $x = 123; \my $y = \$x; say $y;
'
Aliasing via reference is experimental at -e line 3.
123

$ perl -M5.022 -e'
   use feature qw( refaliasing );
   no warnings qw( experimental::refaliasing );
   my $x = 123; \my $y = \$x; say $y;
'
123

$ perl -M5.022 -e'
   use experimental qw( refaliasing );
   my $x = 123; \my $y = \$x; say $y;
'
123
[download]

$ perl -M5.026 -e'
   my $x = 123; my \$y = \$x; say $y;
'
The experimental declared_refs feature is not enabled at -e line 2.

$ perl -M5.026 -e'
   use feature qw( declared_refs );
   my $x = 123; my \$y = \$x; say $y;
'
Declaring references is experimental at -e line 3.
Experimental aliasing via reference not enabled at -e line 3.

$ perl -M5.026 -e'
   use feature qw( refaliasing declared_refs );
   my $x = 123; my \$y = \$x; say $y;
'
Declaring references is experimental at -e line 3.
Aliasing via reference is experimental at -e line 3.
123

$ perl -M5.026 -e'
   use feature qw( refaliasing declared_refs );
   no warnings qw( experimental::refaliasing experimental::declared_re
+fs );
   my $x = 123; my \$y = \$x; say $y;
'
123

$ perl -M5.026 -e'
   use experimental qw( refaliasing declared_refs );
   my $x = 123; my \$y = \$x; say $y;
'
123
[download]

Upd: Dropped requirement to 5.22 for refaliasing part.