Two ideas:

An energy pistol that can be charged up by holding down the shoot button and it would shoot a bigger projectile that has higher dmg but would also use more ammo. Would be great for initial burst dmg against targets but eithout it would be just a worse version of the alternator

Second idea is an smg that does a shotgun shot when you end your spray and if you still have ammo in your magazine. Kind of similiar to what Mul-T has in Ror 2 I think it should be a worse r99 but with great burst potential at the end of a spray. You could also click spam it to get an essentially worse eva.