I'm not a tax specialist, just someone in a similar situation (self-employed, doing my own taxes as sole proprietor, with a high deductible marketplace plan and an HSA). The last time I had this kind of plan was in 2017, I think, and my memory (and the reason I opted into it this year) was that contributions to the HSA are treated the same as contributions to my IRA: they don't reduce my total income but they DO reduce my taxable income. (On the old 1040, IRA and HSA contributions ended up in that bottom section on page 1, and thus were the last item factored into income to produce the AGI).
My own strategy, then, has been to take advantage of a bit of extra income and the odds of being in reasonably good health to pay a modest amount in premium and to throw what money I can into the HSA to reduce the heavy tax burden of being self-employed, while helping to build some rainy day health savings that I'll be able to draw on in a few years when I'm working less and, maybe, dealing with more medical issues.
Again, not an expert and pretty confident about this, but would welcome a course correction is someone out there were to look over your/my shoulder.
Best of luck.
