While much more can always be said on the topic, I summarized the current academic consensus as well as the links to relevant posts and possible new text finding before in: I've often heard the argument that Vikings had rediscovered North America centuries before Columbus stumbled into the Caribbean. Did they know they were on an uncharted continent? If not, where did they think they were?

+++

In short, the oldest extant written evidence on Vinland, Adam of Bremen's History of the Archbishops of Hamburg-Bremen, is written in the late 11th century Germany, and this account was transmitted also to Iceland as well as Scandinavia later by the time when the Icelandic scribe decided to put the text of Vinland sagas down on parchments in front of him, so it would be almost impossible to reconstruct the original, pre-Adam oral tradition based on the extant evidence.

On the other hand, few mainland Scandinavians and Europeans apparently paid much attention to the description of Vinland in Adam's work in later Middle Ages (at least in the 15th century). According to Adam and other early traditions, Vinland was certainly wonderful, but just an otherworldly island among the ocean that few people actually knew how to sail for it.
In other words, pre-Vinland sagas (and as well as Vinland sagas) version of the tradition on Vinland was, so to speak, St. Brendan's voyage in medieval Irish legends.

There is evidence that some rumors of the existence of Newfoundland, although vague and frammentary, did reach Southern Europe. There is a mention to "the country they call Marckalada", to the west of Greenland, in the Cronica universalis written in Northern Italy around 1340. The toponym "Marckalada" is probably the "Markland" from the Saga Grœnlendinga.

This paper contains (between pages 3 and 4) a transcription of the relevant passage:

https://www.academia.edu/50743474/Marckalada_The_First_Mention_of_America_in_the_Mediterranean_Area_c_1340_