Reddit mentions of Glasslock Food-Storage Container with Locking Lids Oven and Microvave Safe - Rectangular 37oz

I have a couple of glass-lock containers I got off amazon, I can find a link if you want but there are lots with good reviews (sturdy/leakproof even for liquids). They can handle freezer, microwave, whatever; I just take the tops of to microwave.

I find that the ~3 cup version is my go-to for single meals, with the smaller one working for snacks or small sides. And then I have a large version, maybe 6 cup capacity, that I use for large portions of leftovers in the fridge to be portioned out later.

It seems like you want one single container to work for your lunch every day, which I applaud from a simplicity standpoint. Personally it would bother me to put a couple cups of soup in a container big enough to hold a couple slices of pizza! So I like the flexibility of multiple sizes like these.

I don't know if that's the kinda think you're looking for but I absolutely love them. I would never send a friend home with leftovers in one of these these, I'd have to follow them and get it back immediately,

I can't speak to the pyrex snapware boxes, but I have used some glasslock brand containers for years and years and they've been perfect.

Looks like they have some in the size you want

I toss my lunch in my purses so I need to know my food won't leak and I prefer glass so I use Glass Lock & Lock containers.

r/MealPrepSunday always recommends containers from Amazon like this.