Its normal but yes exhausting.
Given he has been ill and has a new sibling his need for extra feeding sounds normal.
As you say you dont want to do it all rhe time. How much does he likw routine? Ie could you arrange certain times (roughly) a day where you will feed him? Maybe instugate a bit of a pattern? With mine they had been nursing three ish times a day and then fed more when baby was born. Tjey see the baby feeding all thw time and so want to feed themselves.
I said mornnings, evenings and naprimes and then let them.have other feeds ie when they needed that comfort.
I tried to get them settled doing something before i fed the baby, yes sometimes infront of the tv.
I also had a special box, a decorated shoe box that i filled wirh little toys and treats and some littlw freddo bars, cereal bars, matchbox cars, bubbles, tat from poundland, new books etc. Basically anything i thought they woyld like. The little individual playmobile men you buy in a packet were good, ballons etc.
This box came out at baby feeding time so they got somwthing special for them, they could either nurse themselves orhave a treat frim the box!
Yes tantrums need to be ignored but imo he is too young to totally ignore, he cant control.his emotions or reactions so a cuddle, reassurance and distraction are totally age appropriate ime. my dd just turned two a fortnight ago and she needs a bit of teassurance when she tantrums, its not rewarding the tantrum, she doesnt get what she wants but i do acknowledge her feelings and offer reassurance as they are often overwhelmed and freaked out by the strength of their own feelings.
How good is his speech?
Also how well do you think he woyld respond to an egg timer or alarm.for feeding ie to keep the length of the feed short? Something visual and somwthing at the end of the feed that is positive. Hell bribe him with a chocolate buttom even at the end of the feed?
Does he have a big boy cup? Is there anything else he likes to drink?
He is off his food as he has been ill? At this age several small snacks are better than big meals, i would be offering but not making a fuss if it doesnt get eaten. If he likes baking maybe involve in food prep? He could spread soft cheese on bread and help chop cucumber, banana etc. Or whatever i was thinki.g of easy minimal prep food.
I think the thing to remember is this is a phase, made harder by illness and a mew sibling amd this time of the year means being inside more etc which is not good.
Getting out more helped as toddler less likely to ask to nurse when.out, library, park, walks etc. Do.you have a garden he can play out whilst you supervise from inside?
Nursing manners...asking nicely, explain to.him tantrums are not ok.
Have a look at 'the leaky boob' and 'analytical armadillo' on fb. Also there are some books on tandem feeding worth reading.
Its exhausting but i promise you it gets better!!
Will they both nurse to sleep so you can nap? I used to take mine to bed and get them both to sleep or at least baby andhave pile of books etc for toddler ao we could snuggle and be cosy.
If you have a strong nursing aversion habe you tried breathing exercises or distraction techniques(for yourself)