Headers not showing in Arabic letter

I am trying to create a letter template in Arabic for my business. I am trying to include headers and footers using the fancyhdr package. However, whenever I try to compile the document it shows the content without headers. Here is the code and the resulting document:

documentclass[12pt, a4paper]{letter}
usepackage[a4paper,margin=1in]{geometry}

usepackage{lastpage}
usepackage{fontawesome5}
usepackage{fancyhdr}

pagestyle{plain}
rhead{تعاونية }
lhead{الرئيس: }

renewcommand{headrulewidth}{0.4pt}
renewcommand{footrulewidth}{0.4pt}
setlength{headheight}{14.5pt}

makeatletter
letps@emptyps@plain
letps@firstpageps@plain
makeatother



usepackage{graphicx}
usepackage{fontspec}
usepackage{setspace}
usepackage{polyglossia}

setmainlanguage[calendar=gregorian,hijricorrection=1,locale=morocco]{arabic}
setotherlanguage[variant=british]{english}

setmainfont{Amiri}

usepackage{setspace}
onehalfspacing

address{}


begin{document}
begin{letter}{ألي السيد}
opening{textbf{الموضوع: فلاحي.}
 
 سلام تام بوجود مولانا الإمام:}


end{letter}

end{document}

Thank you in advance.