If you go to https://philanthropies.churchofjesuschrist.org/byu/ and press the "Give to BYU" button, you can click in the search field, click BYU, click Athletics, and you literally get 46 different specific athletic related fund accounts that you can give directly to, including BYU Football.

Here is the list:
Athletic Director's Circle - BYU
Athletic Directors Fund - BYU
Athletic Scholarships - BYU
Athletics General Fund - BYU
Built 4 Life - BYU
Coaches Circle - BYU
Cougar Club - Bronze Cougar $250
Cougar Club - Golden Cougar $1,250
Cougar Club - Platinum Cougar $2,500
Cougar Club - Regular Cougar $125
Cougar Club - Silver Cougar $600
Cougar Club - Y Fan $60 (formerly Young Alumni)
Cougar Club Legacy I - ($10,000 initial gift OR $1,250 renewal)
Cougar Club Legacy II - ($25,000 initial gift OR $1,500 renewal)
Cougar Club Legacy III - ($50,000 initial gift OR $2,000 renewal)
Cougar Club Legacy IV - ($100,000 initial gift OR $2,500 renewal)
Cougar Club Legacy V - ($250,000 initial gift OR $3,000 renewal)
Cougar Club Legacy VI - ($500,000 initial gift OR $3,500 renewal)
Cougarettes
Curtis Rex Pugsley Track Endowed Fund - BYU
Football - BYU
Football Varsity Club - BYU
Men's Baseball - BYU
Men's Basketball - BYU
Men's Golf - BYU
Men's Soccer - BYU
Men's Tennis -BYU
Men's Track & Field - BYU
Men's Volleyball - BYU
Swimming & Diving - BYU
Varsity Club - BYU
Winner's Circle - BYU
Women's Athletics General Gifts - BYU
Women's Basketball - BYU
Women's Golf - BYU
Women's Gymnastics - BYU
Women's Soccer - BYU
Women's Softball - BYU
Women's Tennis - BYU
Women's Track & Field - BYU
Women's Volleyball - BYU
Men's Lacrosse - BYU
Men's Rugby - BYU
Racquetball - BYU
Women's Lacrosse - BYU
Women's Rugby - BYU