Encryption and Upgrade questions

Well I finally bought myself a new laptop and hopefully I'll be enjoying this Asus TUF Dash F15 i7 a lot more than my main old Toshiba laptop that is still running from 2011!

Now I noticed that Windows 11 Home Single Language has 'Device Encryption' but not 'BitLocker Device Encryption'. I was hoping to partition the main SSD (NVMe) and have two partitions with the C drive and a data partition both encrypted but this does not look possible. Also when I put in a USB stick there was no option for BitLocker.

It looks as though I may have to pay for an upgrade to Windows 11 Professional but I'm not sure which is the official link for it? I'm not sure if upgrading would change my warranty with Asus?

On another point it seems like when I created my Microsoft Account on installing Windows 11 Home the C drive was automatically encrypted and the recovery key is saved somewhere on my Microsoft account in the cloud in case I lose it. I read that some users prefer to uninstall their Microsoft Account and just have a Local Account. Not sure about this. If all the recovery keys are stored online is it not better to start again and remove the Microsoft account altogether?

One other point is that I don't wish to unscrew the laptop to install additional storage as it's only it's second day in service and I may invalidate the warranty. It looks as though buying an external 2TB SSD is too expensive so I may use an external 2TB HDD to 'read' the data and use the laptop's SSD to 'write' the data for now. I need to test this and of course this isn't an ideal solution but better than risking invalidating the warranty on a new laptop.