The issue is that if you have a design of an actual product in mind rather than just learning, then at current climate you have to secure all needed stock (+30% just in case) of chips before you even start. This is because even if you successfully complete the prototype, everything is working and ready for production run, chances are you will have to wait year or longer for the chips to come and that is not guaranteed. Sometimes you could buy it from unauthorised distributors, but they ask hefty premium that only makes sense if your product is niche enough so you can still make profit even after using now an extremely expensive part.
Also investing time in learning a platform is risky, because you don't know if in a year or two they decide to make the platform obsolete.
Stock for these seems OK, at least in the UK where I am based. It was ordered from Farnell. Mouser also have them in stock, but the situation may be different in other countries.