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I realize this is a super basic question, but I haven't used a gps and i guess it's time for me to enter the 21st century. What phone program would I need to follow or add a gpx file to LoJ? Would On X, Gaia GPS,or Caltopo work? Any other recommendations?

As far as I know CalTopo is the best, but I'm nowhere near an expert.

CalTopo does just about everything I want short of hyperlinking to a web page from waypoints. I have a subscription which allows a lot of extra features like saving map layers offline and unlimited maps (plus you get weekly satelllite imagery layers which are worth the price alone for someone like me). There is a geojson export specifically for importing LoJ waypoints into CalTopo.
https://listsofjohn.com/export

Example once imported:

Thanks. I'll try it out.