Thanks for the additional information! Just don't underestimate the size of northern Sweden. The places you mentioned in the first post cover a large are, roughly half of Sweden. Or about the size of Great Britain.
If you enjoy hiking, you have some great opportunities nearby. Höga kusten (The High Coast) offers many hiking options. Skuleskogen national park 25 km south of Ö-vik is worth a visit. https://www.sverigesnationalparker.se/en/choose-park---list/skuleskogen-national-park/ Rent a car for a day and go hiking there.
Another nice excursion nearby is the island Ulvön, a bit south. Ulvöhamn, the main settlement on the island, is a cute fishing village. Take the bus to Köpmanholmen, 15 km south of Ö-vik, from there it's a 1 hour boat trip to Ulvöhamn. There are a few places to stay on the island and a couple of restaurants, so it can be a nice weekend trip.
And if you enjoy culturally rich food, keep in mind that Ö-vik is in the surströmming-belt, so if you're brave enough to try surströmming, you have the chance.
Looking further afield, the obvious answer is Umeå. It's 45 minutes away and a great day trip, a lovely city in my opinion. A bit further south, consider Härnösand or Sundsvall.
If you want to go further away, Vemdalen is mostly famous for being a ski resort. So maybe not the best place to go to in August. Åre is also well known as a ski resort, but it's a proper town as well and a popular summer destination for hikers. Luleå is also worth a visit, it's a charming town in many ways. Could be a great stop on the way towards Kiruna. And if you want a long hike, Abisko west of Kiruna is the start (or end) of probably the most famous hiking trail in Sweden, the 450 km Kungsleden. There are also things to see and do in Östersund. An option could be to continue via Umeå and Luleå to Kiruna. Then take Inlandsbanan, https://res.inlandsbanan.se/en , south to Östersund. And after that continue south, or head back to Örnsköldsvik.