I have an old Ipad gen.2, that can't be updated to the latest IOS, and wonder if I can use it in either sim, to use for ie. Little navmap, MCDU, Simbrief, the new Msfs 2024 flightplanner  etc., or does it need a newer IOS?

If not, will a cheap android tablet be an alternative?

Just knowing how my iPad from 2016ish behaves if I plug it in and turn it on, I would recommend getting a little Android tablet. iPads of certain generations don't exactly age gracefully and the battery performance and iOS performance after updates is pretty atrocious.

I thought of getting an Android tablet too, but opted for another laptop I can use during business trips. 

I have an ipad air 2 that I leave connected to the charger. It runs the aviasoft PMDG CDUs just fine as well as Navigraph Charts and Simbrief running as an app. I think there's a Fenix MCDU feature that does not seem to do well on this device, but I never tracked down if it was a hardware issue or something I was doing wrong.

Hope this helps. Give stuff a try and see if it works.

I have an old iPad gen 2 connected to the charger and via Wifi to my simulator as MCDU, FMC to my FBW A320, ATR, CJ4 and MD11, it works perfectly.

I would go the app store on your iPad and see which OS version in the minimum requirement for the particular apps that youtube and others swear are the ones to get. A PC touchscreen is another idea.

I use this: https://www.amazon.com/gp/product/B09JFGJD78/

It has a real stand that won't collapse when you touch the screen and is a brand name item.

 

 I have an older ipad and have FlightRemote Cockpit HD App installed ideal for GA flying.