Example script using Pandas/GeoPandas to help @jqtrde. See https://gist.github.com/jacquestardie/ba32c3304bbe7d8e85b5

converted.geojson

{"type": "FeatureCollection", "features": [{"geometry": {"type": "Point", "coordinates": [-67.5667647785632, 44.92662008087262]}, "type": "Feature", "id": "0", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.57431718872728, 44.92251968199407]}, "type": "Feature", "id": "1", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.49904975129168, 44.931871400375485]}, "type": "Feature", "id": "2", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.50305560217842, 44.93475062348244]}, "type": "Feature", "id": "3", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.57861402660917, 44.918351294222894]}, "type": "Feature", "id": "4", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.63033546770116, 44.98537313256866]}, "type": "Feature", "id": "5", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.5162499184765, 44.96618677405628]}, "type": "Feature", "id": "6", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-67.51007318842774, 44.97015722810917]}, "type": "Feature", "id": "7", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-68.069497177844, 44.84055111538136]}, "type": "Feature", "id": "8", "properties": {}}, {"geometry": {"type": "Point", "coordinates": [-68.10897598316643, 44.94785579668702]}, "type": "Feature", "id": "9", "properties": {}}]}

jqtrde.py

import pandas as pd
import geopandas as gpd

import fiona.crs
from shapely.geometry import Point

# Open the file as a table. Name the two columns as x and y
df = pd.read_csv('raw.txt', header=None, names=['x', 'y'], sep=' ')
# Convert to shapely Points and to a GeoDataFrame with epsg 26919
geoms = df.apply(lambda row: Point(row['x'], row['y']), axis=1)
gdf = gpd.GeoDataFrame({'geometry': geoms}, crs=fiona.crs.from_epsg(26919))
# Convert to lon/lat
gdf.to_crs(epsg=4326, inplace=True)
# Store GeoJSON
with open('converted.geojson', 'w') as f:
    f.write(gdf.to_json())

raw.txt

613105 4975798
612517 4975332
618438 4976478
618116 4976792
612186 4974863
607978 4982238
617011 4980265
617490 4980715
573541 4965659
570290 4977544