MSuzuqi San,
As I understood, you are both new to GNU/Linux and you are concerned with
your security and privacy. Good security requires good understanding of the
system. You can always change your GNU/Linux distribution or tune your system
settings for best security later, when you have learned better. It is free.
But you can't change your hardware for free. Also, specialized hardware (e.g.
libreboot laptops) are relatively quite expensive than their equivalents. So,
I would suggest you defer specialized hardware purchase for a later time,
when you have learned more about security and GNU/Linux, so that you will
know exactly what hardware/system you want to buy.
I would suggest just start with a typical (normal) PC or laptop and learn
GNU/Linux (and security setup) on it. I think it is the most cost efficient
way for you.
I am using GNU/Linux for a long time, I am also concerned with my security
and privacy, but I am still using a typical PC. To give a rough example;
* With Windows you have 10%-30% security (depending on your expertise)
* With GNU/Linux (typical PC) you have 50%-95% security (depending on your
expertise)
* With GNU/Linux (libreboot PC) you have 50%-%97 security
* With GNU/Linux (special hardware[*]) you have 50%-%99 security
(the % numbers are just symbolic, to give you a rough idea)
[*] Please see;
https://www.crowdsupply.com/eoma68/micro-desktop
http://lists.phcomp.co.uk/pipermail/arm-netbook/2017-December/015062.html
http://rise.cse.iitm.ac.in/shakti.html
http://rhombus-tech.net/riscv/shakti/m_class/
If you install non-free programs (some distributions offer such options) or
some other questionable programs (even though they are free) on GNU/Linux,
your security level can go down (this is why I have shown a large 50%-99%
security range). For "questionable program" examples please see;
https://trisquel.info/en/forum/web-browser
Therefore, whether you use standard PC (cheap) or specialized PC (expensive)
it will only change security level by 2%-4%. For this reason, I suggest you
start with a standard PC or laptop.
Wish you the best. :)