Can inhaling your own carbon dioxide by wearing a very tight home made mask which doesnt let air to pass in or out easily for a longer period of more than a year give you alkalosis?

No. Inhaling too much carbon dioxide may cause respiratory acidosis, which is the opposite of alkalosis. https://www.healthline.com/health/alkalosis Also, very few homemade masks are tight. Any respiratory acidosis should be temporary. You should recover your normal acid-base balance each day while you are home with your mask off. If you have alkalosis, look elsewhere for the cause.

You are highly unlikely to retain carbon dioxide while wearing a cloth mask. Retaining carbon dioxide may cause acidosis but not alkalosis. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get Covid vaccine. Wish you good health!