I see you have no responses, so I will take a stab at answering.
Växjö - I haven’t been to Växjö, but did spend a night in the glass region in the town of Nybro. I’d research to see if any of the places actually have glassblowing demos. I went on the offseason and this wasn’t an option. Many of the works are owned by Orrefors Kosta Boda, so if you got to more than one of the glassworks, try to choose an independent. You can get some very good deals on seconds; I have some lovely Orrefors wineglasses that retail for about $50 in the States that I paid about $10 for.
Öland - There is plenty to see around the island. Three days will be a leisurely stay. You could aldo consider visiting Kalmar on your way to Öland if you end up spending 2 nights in the glass kingdom. Kalmar is fairly compact and it would work as a lunch stop with a side trip to the castle.
I haven’t been to the places in the middle of your trip with the exception of Västervik which is a cute town worthy of a lunch stop.
Are you sure you want to stay in Uppsala as opposed to spending more time in Stockholm and visiting Uppsala as a day trip? It is a very short train ride from Stockholm so works well as a day trip. It is a nice university town and the Linneaus garden is very nice in the summer. Sigtuna is tiny and I didn’t really feel that it was a ”must see”. I combined it with a visit to Skokloster by boat.
I personally think you are shortchanging Stockholm which has many lovely places to walk plus access to the whole archipelago. Tantolunden is a nice place to walk to see the small garden allotments. https://www.timeout.com/stockholm/attractions/tantolunden
Also take a walk along Monteliusvägen for great views. My favorite place to eat lunch in the summer is Rösendals Trädsgårdscafe on Djurgården. It is a great cafe set in an apple orchard and garden with wonderful baked goods. Here is some info https://www.rosendalstradgard.se/in-english/
