Sauna / cold plunge - Tax Deductible for STR?

I started renting out my primary residence on Airbnb this year, 2025, and have already had it occupied for 50+ days that's generated $6,000+ of pre-tax income.

 

I'd like to know what the tax implications would be if I bought a sauna and cold plunge tub this year, 2025, for guests to use. I found this answer from ( @Tehaleonie / linked below) about hot-tubs but the OP had bought their hot-tub in the year before listing their property. If they are tax-deductible, can I deduct their entire cost if I never use them? How would I fill out next year's Schedule C?

Things to note, this is my primary residence currently and I plan on having it rented out around 100 days this year but in 2026, I plan on moving and making this a full-time STR. 

 

Deduction of hot tub if bought 1 year before renta