This probably sounds like a dumb question, but I am unable to visit any temples as I don't live in India. That being said, any effort is probably better than none at all. Would Nama jap of Narayana (Vishnu) be helpful like that, even if I don't visit his temple?
Yes, even if you don't chant with devotion, Lord will listen to you because he is all pervading and gives knowledge to you in form of Paramatma residing in your heart.
When people properly glorify the Supreme Personality of Godhead or simply hear about His power, the Lord personally enters their hearts and cleanses away every trace of misfortune, just as the sun removes the darkness or as a powerful wind drives away the clouds.(Srimad Bhagavata 12.12.48)
To those who are constantly devoted to serving Me with love, I give the understanding by which they can come to Me. To show them special mercy, I, dwelling in their hearts, destroy with the shining lamp of knowledge the darkness born of ignorance.(Gita 10.11-12)
One who chants the holy name of the Lord is immediately freed from the reactions of unlimited sins, even if he chants indirectly [to indicate something else], jokingly, for musical entertainment, or even neglectfully. This is accepted by all the learned scholars of the scriptures.(Srimad Bhagavata 6.2.14)