Probably not huge savings, but:
We do meatless Mondays. I try to sneak in more meatless days, but my husband doesn't always go for that. We do it for health/environmental reasons, but veggie-based proteins are much cheaper than meat-based protein.
During the early days of COVID, I got really good at making creative pantry meals. Based on what I had vs. what I'd like to go buy fresh (we used to go to the store daily).
And we always buy blocks of cheese and grate it. Way cheaper than buying shredded cheese. And tastes better, IMO.
All three of these ideas work out to some great lentils and cheese recipes. 😉