Do I understand the sarcastic quotes around "rent" to mean that you will be charging well below market rate, e.g. just enough to cover HOA and taxes? If so, be aware that you will not be able to treat this as an investment property for purposes of deducting business expenses and depreciation. The IRS will, rightfully I should add, be extremely skeptical that this is a bonafide investment. Especially since you will be making this favorable deal with a relative. With the recent cap on SALT deductions this could cost you dearly.
Tax issues aside, you need to calculate what it would cost you to have net worth tied up in an underperforming asset (the condo). In other words, there's an opportunity cost to not having that equity put to work in other investments. Let's say it's worth $100k more than the mortgage + transaction fees. Invested this could return 8-10k annually, vs. zero if you're just breaking even on the condo. Additionally, there's the issue of maintenance, wear and tear, and depreciation.
My advice: Don't conflate primary residence homeownership and the landlording business. If you want to trade up to a bigger house and you're okay with the added expense, and what this does to your FIRE plans, then go for it. If you want to be in the landlording business, does your condo actually pencil out as a good investment? If so, then run it as a business. IMO, more often than not it makes more sense to just sell the condo, claim the primary residence capital gains exclusion (assuming you meet the requirements), and cash-in out the appreciation completely tax free.