I completed the GR30 by the standard classic route end of July 2022 in self supported fashion. My stages were 1. La Bourboule to Aydat, 2. Aydat to Besse, 3. Besse to Saint Genes Champespe and 4. Saint Genes back to La Bourboule. This meant running with a ruck sack of approx 6 kg and staying in Hotels each night, and running on average 50 km per day.
I ran on my own resupplying in villages along the way. For water I filled up from streams, the water is very good in this region. I would recommend insect repellant for second half of my stage 3.
I had great weather which was useful as otherwise certain sections would have been very muddy (stage 3 notably) If you have the time I recommend spending some time in Murol and visiting the musée des Peintres de l’Ecole de Murol. If you need a miracle in Besse there is a place called the “Miracle court “ so go there. My total run time was about 29 hours to well done to the supported FKT’s.
A super loop in really unique scenery of volcanoes and lakes in the middle of France. Highly recommended.