You didn't say where your departure point is - Lisbon is not some outpost on a remote island, there are, at least from my end, a lot of connections. https://www.expedia.co.uk/lp/flights/vie/lis/vienna-to-lisbon
well, I must live in a privileged area - you say train takes days: Vienna to Lisbon is a little over 7 hours. https://www.cleartrip.com/tourism/routes/ii/vienna-to-lisbon-route.html