@1Louder, I prefer the Caltopo website to the Gaia one but that's just me. As I have said in other threads, I use my truck to get me remote to then start my human powered exploration, whatever that may be. As such I'm using the freehand drawing tool to create my own routes sometimes offtrail or using long abandoned trails. Caltopo works great for that. One nice feature is that you can "print" the map to PDF which i do and print out a paper copy but the PDF is a GeoPDF so it is georeferenced and you can open the custom map in the Avenza Map app on your phone and see where you are on your custom map.
As for moving the route you created to a mobile device here's how I do it. First, I'm logged into Caltopo using my Google account. You can use other accounts. I save my custom map to my account. Then I go to Export and Download a GPX file. I then move that file to my Dropbox folder. Open Dropbox up on your phone (iPhone in my case) and click on the GPX file. It will say No Preview Available. Click on the three dots in the upper right hand corner and select Export. From there scroll through till you see Copy to Gaia GPS and click on that and it will import it into Gaia. Presto, you're done. Sounds hard but takes seconds.
As for moving the route you created to a mobile device here's how I do it. First, I'm logged into Caltopo using my Google account. You can use other accounts. I save my custom map to my account. Then I go to Export and Download a GPX file. I then move that file to my Dropbox folder. Open Dropbox up on your phone (iPhone in my case) and click on the GPX file. It will say No Preview Available. Click on the three dots in the upper right hand corner and select Export. From there scroll through till you see Copy to Gaia GPS and click on that and it will import it into Gaia. Presto, you're done. Sounds hard but takes seconds.