I use an ironing chair with a little plastic footstool for my feet so that I can sit at the cooker or kitchen surface as standing usually makes my HR too high and occasionally too low.
When I'm by myself I rely on the slow cooker. I sit at the dining table to prepare vegetables like squash, carrots, celery, sweet potato and I put them in the potpot, plus stock and fresh or dried herbs and some meat like steak or chicken. When I didn't eat meat I'd add pulses and/or beans. I leave that on for hours and then have it with green beans that I put melted butter on. This type of meal usually lasts me a few days.
I also eat bagged salad with meat or fish, olive oil or dressing, and sometimes cheese or hard boiled eggs with mayo. I'll sometimes have a piece of gluten free bread with it. This is the easiest meal for me if I can't prepare anything much as you can just chuck it all on a plate.
I do like homemade soup so I sometimes eat the last of my stew as a soup either blended or chunky.
I buy gluten free breaded fish that goes in the freezer, salmon and chicken also in the freezer - all can be put in the oven and then just eat with some boiled vegetables with butter, mayo, or ketchup.
I find preparing food food a d feeding myself is pretty much what I am using my energy for... It's my priority and I hinge it around resting to prepare to do it, during it and afterwards.