I lived a year in Vilnius and after the usual struggle to get connected found the startup community there quite thriving. Still, most of my friends where expats.
You can live comfortably on 1300 EUR/month. (Average salary is 1000 EUR, but probably a bit higher in Vilnius).
To evaluate visit first in winter because it’s the worst time.
As a local I can confirm, Vilnius has became very strong with its startup community. A lot of international businesses are moving in, a lot of big companies are already in. And that all gathers around the smaller companies and startups.
Super cheap 1-gig internet, super cheap unlimited data mobile LTE / 5G, great food and people. Accommodation is somewhat average, 500-600 euros for a flat in the city centre on average.
I've been living in Vilnius (and surroundings) for the past two years, and I would definitely recommend it. The city is very cozy, well kept, and relatively cheap (small flats in the center run for around 500€/month).
Vilnius (and Lithuania in general) also has really great infrastructure - 1Gbps unlimited FTTH costs less than 20 EUR/month, 4G penetration and prices are better than almost anywhere else in Europe.
With regards to salary, try bigger companies. 2500 EUR/month net for a decent mid-level engineer is the lower bound of what you can get if you shop a little.
You can live comfortably on 1300 EUR/month. (Average salary is 1000 EUR, but probably a bit higher in Vilnius). To evaluate visit first in winter because it’s the worst time.