My Bose S1 is really perfect for me, and could be for you too if you need 3-channels.
I have what Captain Jim recommended above.
Attachment 40099
I also use my beloved Azden FMX-22 2-channel battery-powered field mixer, clipped to my belt.
Made in Japan, it supplies the +48v phantom power to my tiny clip-on DPA condenser mics.
Of course you can turn it off for dynamic mics.
It can mix both my voice and guitar into one channel, freeing up the other channel on the Bose S1 for your other vocalist.
It's also very nice to have the mixer controls at my fingertips when busking instead of having to stop and reach down to the ground - especially to quickly fix feedback.
The sound is crystal clear; now I just learn how to sing.
The mixer's regular price is $309, but Adorama is currently having a 4th of July sale, so it's only $249 - a really great deal!
With $1,000 budget ... $600 for the Bose + $249 for mixer = $849, leaving $251 for taxes/shipping or whatevs.
https://www.adorama.com/azfmx22.html...urce=adl-gbase
Attachment 40101