Puyo Puyo gummies have actually been a product in Japan for several years. You can find them in convenience stores. I haven't picked them up in a long time, but I think they're still doing the crossover with Tetris where you get both Puyo Puyo- and Tetris-shaped gummies. Look up "Puyo Puyo gummies" or ぷよぷよグミ if you want to check them out.
I'm not sure if this is the kind of answer you were looking for, and I don't know if they would sell very well, but I would love to see more branded games from Sega Toys. You could make a great electro-mechanical game based off of Super Monkey Ball for instance, where you have a completely enclosed touch screen panel that you can tilt, with an AiAi marble that the screen can detect. The screen displays ground, sky, and a goal; if your marble touches the sky you lose a life and if it touches the goal you go to the next level and the screen displays a new layout. Super Monkey Ball was interesting in that you controlled the ground, not the ball itself. I think you could make a neat toy out of that.
Since the experience can't be fully recreated on consoles or handhelds, it'd be fun to see a miniature Hang-On where you can actually control the bike on-screen using a tiny, handheld, plastic bike model. A Space Channel 5 Simon game... a Seaman virtual pet / buddy / fortune teller... I feel like you could do something really cool with Rez involving music visualization somehow, although I wouldn't want to cheapen that brand.
In terms of things like foods, Puyo Puyo gummies really are a homerun idea. Super-popular franchise (in Japan) and a product that matches the design and demographic perfectly. I can think of other OK ideas (like some kind of rattly candy that and a powder that changes its color or something like that when you shake it in a Samba de Amigo-branded maraca) but not ones that incorporate currently popular characters other than Sonic, and doing Sonic almost feels like cheating, haha. I have always thought it was ridiculous they never made a real, full-scale Sonic (s)Pinball machine, though. Back in the Dreamcast days you could've made a Furby-like Chao toy, too... could've even given it VMU compatibility with your real Chao.
But for 100% tacky marketing schlock, there's always your NiGHTS-branded dreamcatcher.
