Recommendations for France

Greetings, humans.

My partner and I are headed to France this June.  We'll visit family in Bretagne and then have a good chunk of time to explore the country.

Top of the current list consists of a lot of the southeast.  Any recommendations, advice, words of warning, guidebook beta, etc. would be most appreciated.  We're looking primarily for sport and bouldering.

Thanks in advance.

I'm writing this as I go along so sorry about the waffle...

Where will you be based in Brittany? There's a lovely crag called Pen-Hir jutting out of the sea an hour south of Brest. It has about 200 routes both sport and trad of all grades (though mostly in the 4-6b range) and is such a cool place to be, climbing with the sea behind you is a wonderful experience. Part of the crag can only be accessed by abseiling. Guidebook should be available at the Office du tourisme in Camaret-sur-Mer. While there I strongly recommend going to the Veryar'ch beach (the one to your right in a sort of a cove when driving away from Pen-Hir), it's large, usually quiet (except on weekends) and has some cool rock formations. The Pen-Hat beach (towards pointe du Toulinguet) is also worth checking. I understand there's excellent kayaking that takes you to amazing and colorful flooded caves all around the peninsula.
There's a lot of beach bouldering on the northern coast of Brittany, especially around Kerlouan. Rough granite with supposedly thousands of problems. There's a free online guidebook but it's somewhat hard to decipher.

It's a big drive from Brittany to the southeast so I'll suggest three stop-off points:
-Font: June is usually too hot to climb hard but you can always find shade, there's loads to go at at all grades, it's low season (except on weekends) and if you like bouldering, well, it's like a pilgrimage, that's virtually where bouldering started. The place really is massive. Happy to show you around should you come this way.
-Auvergne: there's some brilliant short, bolted multipitch (3-4 pitches, 100m) on volcanic rock, like Dent de la Rancune (6a and up) and Crête de coq (most routes in the threes to fives):

It's relatively high up (1,500m) so stays cool even when it's hot down in the valleys. Weather can be fickle in that area though (that's why it's green after all). Quiet. Good granite singlepitch at Saint-Sauves that's so overhanging you can climb when it's raining (mostly 7a and up). There are other smaller crags here and there, either granite, gneiss, basalt... Guidebook.
-Gorges du Tarn and Gorges de la Jonte: the Jonte has stunning multipitch on wonderful pockety limestone but it all faces south so tends to be hot by noon. The Tarn is mostly single pitch, long pocket-pulling routes, easy to find shaded of sunny areas. Very little under 6b, most routes are in the 7s and 8s. You're also guaranteed to see griffon vultures which is cool. The place is also renowned for its kayaking (though it tends to be extremely busy in summer). Current guidebooks for the Tarn and the Jonte.

As for the southeast proper, Ailefroide is an obvious choice: granite sport (single and multipitch) and bouldering in a beautiful valley with a cheap campground where you often don't need to take your car to go climbing. June is the very beginning of the high season so it's still very quiet. I suggest getting the Briançon climbs guidebook, you'll find it it everywhere (e.g. Approach Outdoor in Briançon, maybe the Bureau des guides des Ecrins in Vallouise/Saint-Vincent). The Ailefroide bouldering guidebook was a bit trickier to find but we eventually found it at the Bureau des guides I think (?). They'll have it at any Vieux campeur as well and hopefully at Approach too.
Verdon is also not to be missed, the south-facing walls will be hot and thunderstorms can be an issue, but if you start early and/or choose more shaded walls (of which there are plenty) you'll be fine. You'll need 2x50m ropes though. There's also single pitch areas, but I'm under the impression that they mostly face south (so will be too hot) or, when they don't, have nothing easier than 7a (see La Ramirole, Hulk, etc.). Guidebook (you'll find it easily at La-Palud-sur-Verdon). I recommend camping at La ferme de Bourras, quieter as it's out of town and the owner is quite a character!
I understand Céüse offers the best single pitch climbing in France at this time of year (it's pretty high up, 1,800m?) but haven't been, I'm sure others will fill you in. There's both a paper and a (paying) online guidebook. The north face of Saint-Léger du Ventoux might be another option but I haven't been either. Most other classic single-pitch venues will be hot in June (Buoux, Orpierre etc).

Let me know if you have specific questions or need more advice!