First of all, hello to all people here

I have got Lenovo Tab M10 HD (2nd Gen) with android 11 as it seems it is the best supported model of tablet.

I've read the page:
https://devices.ubuntu-touch.io/device/amar-row-wifi/release/noble/
and I understand I have to unlock bootloader as explained in
https://unlocktechy.com/lenovo-tab-m10-hd-gen-2-unlock-bootloader
and then follow instructions at
https://snapcraft.io/ubports-installer

However, I have no clarity on unlocking bootloader. The page linked above doesn't provide/link software for linux. I've borrowed windows machine to use dedicated USB-drivers but still the linked file is not exe but some dlls.

Are using software provided by lenovo instead is a good idea? Link - https://lenovousbdriver.com/device/lenovo-tab-m10-hd-usb-driver

Second question, how can I backup my original android 11 in case I've screw something?
I don't want to use google account as I own only one for my job.

I'd greatly appreciate support, I'm new in this.