Patient Gamers

What Remains of Edith Finch, and The Unfinished Swan

I'm not sure if it quite fits but the first game that came to mind was Minami Lane

I haven’t played it myself, but Boku no Natsuyasumi is a game that recently entered my radar, which fits your description quite well. It’s a game I want to play sometime, but I have had other priorities. It’s for PSX.

It’s about a boy in a summer vacation with his family.

Unfortunately there doesn’t seem to be any official English versions of the game, but hopefully you might find a solution if you think the game looks interesting enough to play it.

Maybe the Atelier games would fit the bill? The recent entries, mostly the Ryza trilogy ("Atelier Ryza: Ever Darkness & The Secret Hideout", yeah, the title is a bit clunky) don't have the time limit that used to be a staple of the series. Instead, it is incredibly chill, a JRPG in a relaxed, colorful environment with an actually really fun, puzzle-like crafting system (called synthesis, their take on alchemy), which feeds masterfully into combat and resource collecting. It is very fun, and the game feels like going on a summer holiday with friends as a kid. :)

Surprised TOEM isn't on your list, given the premise is pretty much exactly what you describe. Last I checked it comes up on the first page or something if you sort steam by highest rated.

Lunacid might also be a good game. I think it fits your criteria for me, but that might just be for me.

The first thing that comes to my mind is Summer in Mara. It's a chill, relatively shallow farming sim with fetch quests and exploration.

Some more based on other games you liked:

• Arida - short-ish adventure game with a bigger emotional impact
• Nuts - probably most similar to Firewatch; core gameplay loop is taking pictures of squirrels, but there's some plot development
• A Juggler's Tale - side scroller adventure with some feels
• Deponia - funny point and click adventure series; if you like the genre, try The Darkside Detective (less "summer adventure" more "weird mysteries")
• Manifold Garden - more chill than The Talos Principle or The Witness, with less feels than the first; decent, trippy puzzle game

A lot of nice suggestions already, I'd like to add the Sorcery! games if you don't mind reading and enjoy exploring.
I personally really loved the world it portrayed and the tried so many different ways to finish the story.
Also, it has great maps, and I love maps :)

"What Remains of Edith Finch" could work. And "Man eater." What's more summer than a a shark?

Have you enjoyed any of the recommendations OP? I like your original list/taste and am wondering what else fit the aesthetic

Try Stranded Sails. It's a tight little adventure game.

Alba: A Wildlife Adventure

It's perhaps a bit child-oriented, but is pretty fun, chill, and you can't do more "summer vacation" than that.

The Big Con

Toejam & Earl: Back in the Groove!

Castle Crashers

Here Comes Niko, "the cozy 3D platformer for tired people." You play an adorable sprite leaping around a tropical island chain. I don't think it has failure modes, in general.

Stanley parable ultra deluxe there was a bit in the desert so it fits.

The looker as you played the witness I really recommend this parody

E: +1 to a short hike

Brothers a Tale of Two Sons

Seasons After Fall

A Story About my Uncle

Subnautica

Raft

Ori 1 and 2 maybe