Would be nice. Even with custom ones would be nice also. 

I have not seen a place where you can change the emoji, but you should be able to change the reactions by substituting {yourswesite.com} with your own URL

https:// {yourwebsite.com} /studio/builder_forms.php?page=pre_values&module=system&list=sys_vote_reactions 

i have these ,Font Awesome Pro - iconstyle-duotone

Yes they can be changed, we are using animated emojis, but for animated emojis some phone CPU's are creating problem.