I had a similar experience, with a slightly different approach (mouth tape and a nose dilator) but seemingly similar outcome. I like that you did it just through exercises with no mechanical intervention. Inspiring.
Instead of a mouth tape get one of those moldable plastic mouth guard things from amazon. And mold the hole shut.
Thank you! I saw you mentioned mewing in your comment, they teach you that in some pranayama exercises as well and I agree it’s a great addition. It feels unnatural at first but when you get used to it, it’s almost like bracing your palate with your tongue allows you to pull air in through your nose more smoothly and with more power.
I’ve found this is all really worth learning, even if you don’t have sleep apnea. I feel more clear headed and energized when I can breath through my nose now.