Just from what I have seen other food bloggers doing, kitchen utensils and handy products seem to sell well to this niche. Thinking about things we have personally bought, in my household - poached egg maker, automatic apple peeler, kitchen knives (If you want a great kitchen knife btw, check out the Chinese vegetable knife its now an absolute necessity in my kitchen) just to name a few.
I see it lots of times on Instagram as well - my wife follows quite a few food bloggers and they are always promoting some cool new kitchen implement that either saves you time or makes cooking easier my wife is always like - look at this thing its amazing, look how well it works, can I buy one?
Cookbooks are another good one as well and maybe other alternatives to the box thing you are selling - is there one called hello fresh? Diet plans such as the Joe Wicks diet plan. Something like a slimming world dieting subscription?