Is it true that The Russians in their eastward push eventually reached Alaska but they never entered the territory of conterminous Lower 48 US?

The statement is true. Russian explorers did explore and colonize parts of Alaska, most notably during the 18th and 19th centuries. They established settlements along the Alaskan coast and the Aleutian Islands. However, the Russians never ventured further south into the contiguous United States or the Lower 48 states. Their settlements in Alaska were eventually sold to the United States in 1867 through the Alaska Purchase.