I have had hypertension for many years and am on medication.
I have Covid for the last 4 weeks and was recovering. I was put on oxygen as they believed I had pneumonia. As I started getting better I realized I didn't need the oxygen during the day but only at night.
I then started measuring my blood pressure in the morning and found that if I used a 1 liter setting and slept with that my blood pressure in the morning was lower than not using it. ( I stopped taking medication and monitored the blood pressure, ready to take medication again if it seemed to high.)
Also I started taking cinnamon with rolled oats for breakfast most days and it seems to be lower still. My normal is typically 153 / 94 but today it was 135/87.
So give a little oxygen (use less than 1.5 liters at night) a try.