With Dementia, how much do I need to respond to, and what can I ignore?

My mother has been living with us several years. It's been very hard as she does nothing to help, and requires a lot of work on my part (all meals, cleaning, transportation, organization, etc). I am her sole company as she's alienated everyone else. She has her dogs that love her and she talks to them like they are people, which is fine.

My last issue was working on boundaries and realizing I had no requirement to entertain her. She has to do that herself (as a child I was told only stupid people get bored). She had been playing computer games, watching TV, etc. Now it's just TV. So I felt benefited by this group who encouraged the boundaries (thanks!).

But now we are at a point where she's been diagnosed with dementia, and shows it a little more each day. She comes up with 'ideas' she wants to do. She now wants hip surgery, despite the last ortho visit the doctor telling her she needed to be moving more and able to assist recovery by doing PT and exercises. She doesn't want that, she just wants the surgery. I tried to just ignore the idea, since with covid it's not practical to do it now (if the doctor even would). I ignore it, she keeps talking about it. I encourage her to walk, she says she does. I measured, she walks approximately 25 feet at a time to the fridge, max. Most of the day she's reclined in a chair. She has no muscle.

In avoiding that, she then brings up she wants a new cell phone. She can afford it, but the last one she had she never answered, and eventually just turned off. She couldn't figure out how to use it (it was an easy Jitterbug). She has no need for it, she has the landline and only goes places with me (and my phone). She keeps pestering me about it. She wants me to be the one to make the decision (and thus be able to blame if it's hard to use, or the battery quits, or whatever). I won't.

Every day there's something she wants to do that involves me helping beyond what I already do. I have my own health issues and taking care of her is exhausting.

She has not once helped with anything in the home. Yet last night I heard glass during the night and got up and she said she was cleaning the kitchen for me. She had loaded the dishwasher. Yay, I guess, but I wasn't thrilled. It worries me more that she's up at night getting in to stuff (what if she were to decide to cook?). Her dogs vomit, I have to clean it. She spills something, it's up to me to fix it. If she sees something out of place in my part of the house, she makes a comment but does nothing to help (so to me, just be quiet then!). I'm so sick of explaining.

She doesn't know what day it is, or what time. It's 107 today and she keeps opening her door for her dogs to go in and out. I asked her to keep it shut. Nope. So I'm paying to cool the city, it seems.

The other thing, which is difficult, is that of food. Everything is too hot, too cold, too bland, too spicy. I get it, older people do that. But she wants to have a say in each meal as if this were a restaurant. My go-to response has been to bring her a meal with a few options on the tray, as well as a treat basket she has in her room with fruit, granola bars, chocolate, etc. Hell, I'd be delighted to be served like this. If she complains about the meal, my only other option (same as my son) is a PB&J. But lately she says she's feeling punished by the meals. She's getting what we all eat, no punishment. I'm not cooking like I used to. I do buy her stuff she wants. But each night I get a big frown when she sees her tray.

I'm cooking more frozen dinners than in the past by having found a healthy frozen food line that saves me time. They aren't punishment, my husband and I both enjoy them.
I guess what I'm saying is I'm so tired of complaining when someone does nothing at all. I am questioning how I can stay sane in the future as this will inevitably get worse. How do I turn off the button that makes me feel l have to please her?