does he wear a blazer? get him to keep a pen inside that. They will be extra strict at the start to try and scare the kids into doing things right but also at the moment they aren't allowed to borrow things from each other or the school (certainly at our school) so no pen means he can't write at all. At least if he has one in his blazer he might get told off for ONLY having a pen but he can still do most of his work. Mine leave their pencil cases in their bags and use another pen etc at home.
Yes get bag sorted the night before with timetable in hand to check everything needed is in there, including PE stuff, technology or art aprons etc. Get drink bottle filled and in fridge with packed lunch the night before so it is quick to grab in the morning. Also to start with I don't think it is unreasonable to have a quick check list next to the door (MASK, phone, key, bus card, watch, pen, lunch, drink, glasses or whatever are his key things to remember)
We have plastic folders for each subject as I think it makes it easier. So anything for that subject is in the one labelled folder and all they need to do is look at their timetable and put the right folder in their bag. If all homework goes in the folder straight away (should there be anything on paper but I think most stuff will be online now) then it won't be forgotten
It is hard to work out how to keep on top of things, he is only 11 and he needs to get used to it.
also with masks - my girls take reusable ones (that makes it sound like we have been doing this for ages but obviously we are just getting used to it) so when they come in from school they take out their used one and put it for washing when they take out their lunchbox and bottle. Then after washing their hands they put a clean one in their blazer pocket. Inside their blazer they also have 2 disposable ones in case they forget or lose one or the elastic breaks or something.