Hi Maria,
adding to seewulf’s suggestions - keep in mind that at the moment the trains from Przemysl to Ukraine are NOT running because of COVID stuff… and no date yet announced when they will restart.
So if you decide to use the crossing via Poland, then you have to catch a minibus from Przemysl to Ukrainian border (they leave from the backside of Przemysl station, price maybe around 10PLN, don’t remember for sure). At the border you cross by foot to Ukrainian side. On the Ukrainian side you change a small amount of money, so that you have local currency to take a marshrutka (minibus) to Lviv. The marshrutka is leaving a short walk from the border on the left side from a parking lot. Overall it should take maybe around 2,5 hours this way to get to Lviv from Przemysl (+1 hour time difference!).
Definitely not recommended: taking a direct bus from e.g. Krakow to Lviv. Waiting times at borders can be frustrating long - once my bus was spending 9 (!) hours at the border, while by foot you just walk through or maybe spend 30 mins there…
Regarding scenery the most interesting route to Lviv will be for sure via Slovakia and then from Cierna nad Tisou to Chop by local train as you will pass through High Tatra.. most quick way will be more likely via Poland (see above).
And yeah, you should definitely visit Ukraine, nowadays many young people speak decent English, so no problem to get around and Lviv and Kiev are really touristy places (especially Lviv). Not like 10 years ago :D
Enjoy your trip