Hi, I'm new here and have been looking around too! I have been using 1.65L / 55.79oz / 6.97cups Sistema To Go Box (they have bigger ones), but have been eyeing 1.25L Wagindd box for a while for the sealable compartments. Also I looked up past recommendations on this subreddit and someone mentioned osechi jubako boxes, which look pretty large and are stackable. Some other websites I noticed were Bento and Co - XL boxes, Monbento (p.s. they're seen as expensive), Bentgo, and just amazon or aliexpress. These are just stores that specify bento box, the general idea is just an assorted lunchbox.