the only trouble is finding a large variety of plants/vegetables that are agreeable with digestion and that you actually look forward to eating. in practice this scheme works best if you find the 1-2 starches you handle the best and the 1-2 greens you handle the best and have an appetite for/don't have to force down, but that defeats the purpose you are after here which is as much diversity as possible.
you make a point about using things such as steak, eggs, etc as vitamins on an as needed basis. i have a fundamentally simple diet where i rely on jasmine rice for glucose and whatever lean cut of meat for protein structures that im craving and i will use the traditional peaty foods like liver, gelatinous cuts, oj, coconut oil almost as "vitamins".
i have in the past optimized a diet based around traditional "peaty" foods and used cronometer for instance to make sure all nutrients are met in ratios/amounts that would be considered ideal (low pufa, good zinc:copper ratio, good ca:p ratio, low iron, high glycine to methionine ratio, high vit e, etc) but i found this to be too reductionist of an approach. part of this could be nutritional data on foods is contentious at best but that is a separate issue.
as for maximizing diversity, in my experience i feel much better sticking to the same things everyday that i know i digest and look forward to eating and using those traditional peaty items on an as needed basis. if i haven't had liver in a while, i will have some. if im particularly stressed, its oj with masa cooked in coconut oil, once a week i will dine out usually turkish food and try to get something high in glycine like some lamb, ice cream if im out of the house and there is a shop selling häagen-dazs ice cream bars etc.
if you look at the diet and lifestyles of a lot of centenarians, you can observe they are mostly doing the same habits and routine day in day out for decades and often eating the same things. on the other board someone made a funny remark about how they are some of the most boring goddamn people on earth, or appear to be quite dull. i believe the example used is something like "these are the type of people who if they get to listen to their radio for 5 minutes before bed they will be completely satisfied with what they did that day". i think that is one way to look at it. when i have a routine (diet wise) that i look forward to doing everyday, this is a highly dopaminergic thing and i think there is more value in this than anything else. of course, you don't want to be lacking in important nutrients and precursors, hence using the traditional peaty foods whenever you crave them or as needed. i actually think the peaty foods work best as tools rather than eating them every single day but others get great benefits from daily use.
@GreekDemiGod i remember that thread about applying peat ideas to veganism, iirc it devolved very quickly into people giving OP shit about his b12 status despite him claiming he was doing alright. interesting nonetheless.
slightly tangential but i remember from the old board someone pointed out that pea protein isolate had a relatively "peaty" ratio of amino acids, about half the amount of methionine, cysteine, and tryptophan compared to whey per serving. shame it digests like shit.