I had my Acoustic amp go up in smoke many (30-odd) years ago. No backup. Tiny vocal-only 'PA'. End of gig.
I've always carried a backup since, and never needed it.
Which probably doesn't help...
I had my first ever flu jab on friday. In and out in 10 minutes, and half of that time was just waiting for a few minutes afterwards in case I had a reaction to it.
What other kit have you already got?
I use a little Zoom multiFX - which gives effects, tuner, drum patterns as well - with the other source (phone, MP3 player etc) into its aux input.