For acoustic guitar and vocals, a keyboard amp can serve well.
I used a behringer keyboard amp for many years. It had 4 channels… one at least, dedicated with XLR connector for a microphone.
From my understanding, a keyboard amp has a flat response, meaning all notes up the scale have a pretty much equal volume to accommodate all the sounds a keyboard generates. That feature makes it superior to the guitar amp for vocals.
The guitar amp typically has a bias for guitar.
A new behringer can be had for around $250 to $350…
All the best,