I am in a very similar situation to you. A sudden loss of mobility for me. I struggle with a stick or crutches in the house and a wheelchair outside. This change is permanent for me too, if you want to PM me, I am happy to listen/talk if that would help you.
My children who range from 8yo to 15yo, have struggled in different ways to accept the changes in the household. However, none of my children are autistic, so my solutions might not work for you.
Pocket money is not linked to chores. It is given so they can learn the value of money and how to spend or save.
Each child has family jobs, which they do because they are members of our family. Everyone including parents do family jobs. We repeat this consistently. The family jobs are not done ‘for DH and I’ but for 'the family'.
In our house. Pre my illness
Tidy rooms, put dirty clothes in wash, put away clothes that I wash/dry, clear their plates from the table, scrape plates and stack. Older three make their own packed lunches, youngest has school dinner. Strip their beds. Older two make their beds. Youngest two and me make their bed and mine together. All kids can make simple meals. Youngest (8yo) can only make simple cold salad meals from the fridge and sandwiches, middle kids make scrambled eggs, toasties, noodles etc. Oldest can make spag bol, pizza from scratch (15yo high school home eco classes are great) Often the kids cook for each other.
TBH Tidying their rooms is not adhered to by the youngest two yet, so we are working on it.
Extra jobs Since my illness
Refill my water bottles, bring my handbag to me, make me lunch if they are home, help me on/off with my shoes and bra, put things on/off charge, go to the local shop for bread crisps etc, bring sticks to me, pick up things off the floor when I drop them (this happens a lot), answer the door for me. (Give me a hug when I get sad.) Hoover downstairs weekly, Empty recycling kitchen bins weekly. Carry bags upstairs and downstairs including laundry bags. Put things in/out dryer. Youngest two make their own beds and oldest/DH does mine/ours.
Your situation
In your situation I would first have a sit down and a hug with each child, talk about what has happened in your family and how do they feel about things, so you can give them reassurance and understanding of how they see things and how things will be in the future. I found my youngest two needed things explaining several times, the very youngest still hasn’t accepted that things will not change for me, sigh. Just loads of talking and their feelings.
Separately I would work on consistency and attitude. They should be doing basic jobs around the house as family jobs for the family (not for you or DH) Including fixing their own lunches and feeding the cats, tidying the house.
Give them a short age-appropriate list for 'family jobs' and go over it with them every morning, until they check their list automatically. Keep repeating that everyone has 'family jobs' and we all do them as we are all part of the family.
This just leaves your personal 'mum jobs'. Another short list of 'mum jobs' that they do for you because they love you, that you are their mother and that you need this extra help.
Both of your children are old enough to prep simple food for you. Give them a 'lunch rota', so they know that older child A makes your lunch Monday, Wednesday, Friday and Child B does Tuesday and Thursday. Set the menu the same every week, so each child knows in advance what they are making.
Knowing when and what they are doing would take a lot of the stress and decision-making elements out of the situation.
I really hope things settle for you and I know how hard it is to parent children when you are in pain and tired. Be consistent and get the lists up. 'Family Jobs', 'Mum Jobs' and 'Lunch rota'. After a few weeks, they hopefully will be helping more and things will be less stressful. 