Growing protein

I follow a similar diet - although my one chicken has virtually stopped laying and I'm unsure about whether to get more.
Some of the ideas you've mentioned I've tried and, without wishing to deter you from trying, I haven't been very successful.

Beans for drying -yes, try the bigger ones like Gigantes (like butterbeans).
Sunflower and pumpkin seeds - yes, but most of the pumpkin seeds will have a shell on that is inedible. Some varieties are "naked".
Plenty of other seeds you can grow but mostly they're flavouring, rather than substantial.
Not bothered with amaranth or quinoa as they seem a lot of faff to process.
I have hazels in the hedge but the squirrel usually beats me to them. Chestnut and walnut take years to fruit.
Peanuts only grown for fun.
Fungi - tried dowels, wood mulch, straw and others I've forgotten. Not as easy as they say.

Personally, I try to grow a range of fruit and veg and eat plenty of it. I'd rather buy a bag of nuts than wait 30 years for a tree in the garden. (I do have a sweet chestnut!)

I've dreamt for years about being self-sufficient but it wouldn't be easy without a lot of land and time. No harm dreaming though and doing the best you can.