the ACNH home-designer DLC comes out November 5 for $25, as revealed in the AC Direct today
they ALSO revealed in that Direct that, rather than buying it outright, you can get it for no extra cost if you have the Nintendo Switch Online Expansion Pack, which they announced launches on October 25… at the price point of $50/year—and the Nintendo site lists no 1-month or 3-month prices for it, so you can probably ONLY get it for a year