Sonalder
This isn’t a FOSS apps list but a Free (as free beer) software list for Windows with a bunch of cool FOSS apps https://alternativeto.net/list/29653/my-windows-setup/
You can buy the SMS verification for Telegram on sites likes smspool.net using crypt I currencies such as Bitcoin or Monero.
I’de rather go with Linux Mint Cinnamon or Nobara with their custom GNOME DE
I will rather go with a second hand 2-3 years old premium laptop from a Linux manufacturer such as System76 or Tuxedo.
I think you confuse security and privacy. Samsung are pretty secure from what I saw. They are not private at all however. You can debloat it with adb and maybe tools such as Universal Android Debloater.
There is a couple of guide such as this one: https://linustechtips.com/topic/1402380-ultimate-samsung-oneui-debloat-privacy-customization-guide/