I grew up exposed to French and European media. A few shows come to mind.

Nobody's Boy: Remi

If you can find it, it is a powerfully emotional watch. Unfortunately I don't know if an adequately dubbed or even subbed version is available. It is on YouTube in French but the auto translated subs are awful.

The Mysterious Cities of Gold

A great Franco-Japanese classic. Dubbed versions are out there.

All of the Asterix cartoons are decent and available dubbed as well.

Fast forward in time to the 90s and the show called Reboot is pretty solid. It was made in Canada and I heard that most Americans never heard of it. The first entirely CGI show. Someone rescued the original high def footage recently too so it should be out there.

Robo Story

"Always remember that you are the lowest of the low"

https://www.imdb.com/title/tt0996250/

The Trap Door

"Don't you open that trap door! You're a fool if you dare!"

https://www.imdb.com/title/tt0395413/

Here in Canada we had a couple shows that stood out.

First wasn't Canadian but a British Import but they still showed it a lot here. Count Duckula. Basically this duck is a vampire except he doesn't drink blood, he's a vegetarian. And it was kinda like Doctor Who as there were several different "generations" of Count Duckula would would die and come back and each one had it's own personality with the most recent one, the one the show is about, being a vegetarian vampire.

Next would be held near and dear to many Canadians my age, The Raccoons. A small group of Raccoons that try to save their forest from deforestation by an evil guy. The thing about the Raccoons was while it was a kids show it had plot points that were very mature and sophisticated that honestly anyone of any age could enjoy it. romance, action, humour, etc were all quite mature. Also the ending theme "Run with us" was a hell of a damn banger. But some of the stories did get quite dark. I remember as a kid honestly being scared of a couple Raccoons episodes. also it'd be a crime for me not to post the awesome ending theme: https://www.youtube.com/watch?v=DEkSzcGIfW0

But for whatever reason a lot of Canadian cartoons, like The Raccoons, were quite mature. Reboot and Beasties comes to mind (Transformers: Beast Wars for those in the US). Reboot started out fairly light hearted but the story quickly went to a more mature and dark setting. Same with Beasties. Beasties was interesting because in later seasons they had way more callbacks and plot points from the original G1 Transformers 80s cartoon where the show kinda transitioned from being a kids show to one where Teenagers could enjoy it because they watched the original 80s Transformers. Like it took what happened to the original Transformers and matured the story to the point that the show is so incredibly influential to the overall Transformers lore today that most of the plot and story elements still exist.

finally you have Totally Spies which while likely isn't a hidden gem it is Canadian. It started out as a joint French/Canadian project but the later seasons were done entirely in Canada. a psychologist could have a field day with that show.

Il était une fois... / Once Upon a Time

Look up anything and everything by Švankmajer.

From Nelvana, a Canadian cartoon company that has died just recently:

Dumb Bunnies

George & Martha

Maurice Sendak's Sevin Little Monsters

Best & Bester

Birdz

Blazing Dragons

Braceface

Cadillacs and Dinosaurs

The Day My Butt Went Psycho

The Detentionaire

Jacob Two-Two

Moville Mysteries

My Pet Monster

Stickin' Around

Bob & Margaret

Commited

DeltaState

Claymation, look for Pingu ('80-06)

Other children's media (not animated) you might want: Captain Kangaroo ('61), The Friendly Giant ('58-85), Fraggle Rock ('83-87), Polka Dot Door ('71-2k), and a french show Passe Partout ('77-92). This with the other suggestions should eat some storage

I'm Dutch but we watched a lot of German television. So I grew up on Pumuckl and "die Sendung mit der Maus".

Seabert

It's a French show but it's also dubbed in English which is how I saw it. It's about a guy and his pet baby seal and their adventures. Most of it has a pro-environment angle if memory serves. It's a whacky show for kids. Nobody I know has ever heard of it besides my brother.

I didn't watch Schnappi as a kid, but I stumbled across it when my kids were young and they appreciated the bizarre stuff it showed. I linked one with the full song, but the one I stumbled across back then had Schnappi smoking a blunt (or maybe a cigarette) and reacting to it. I know barely any German, so all I understand is "Schnappi the Little Crocodile".

I found this one a bit weird at times after a couple of Japanese folks introduced me to it: https://en.wikipedia.org/wiki/Usavich

Dr Balthazar

Even though I grew up in Sweden I vividly remember this intro.

Little Elvis was a banger of a kids show.

I watched this last year.

Muzzy in Gondoland

Some weird bits.

bro’Town 2004-2009

La Linea.

Check out Misseri Animations from Italy.

Through the 80s, there were classics like:

A.E.I.O.U.

Red & Blue

Quaq Quao