Russia is a leader in the production of a vaccine against Covid-19. Nevertheless, Lithuania has no plans to buy the Russian vaccine. It is a political decision. The Baltic States have their role in the anti-Russian game. Because of this, they will prefer the quite expensive American or European vaccine but not the quite cheap Russian one.
The Sputnik V is a real vaccine. The vaccines from other producers exist only theoretically.
The US is pushing its partners not to buy the Russian vaccine. It is part of the competition for the market. Americans want to get profit.