I won't be much help here, but here is my experience...
Mac Studio running Ventura 13.0.1
Basecamp for Mac v. 4.8.11
iPhone 12 iOS 16.1.2
I'm a long-time basecamp user, so that is my preferred method of creating GPX files that I upload to my XT. I always create tracks in basecamp using the XT, not routes. I have recalculation turned off on my XT because when I plan a trip, I want to specifically follow preplanned roads or trails (which is why I prefer tracks).
There is an excellent Basecamp Tutorial Course put together by some of the guys on the New England Riders Forum that you can find here:
https://www.newenglandriders.org/learn-basecamp/. I find that Basecamp is the most powerful route and track creation tool out there right now. Explore may eventually replace it, but for now, it's not as capable as Basecamp.
I have an Explore account online and I have the Explore App and the Drive App loaded on my iPhone.
I set up Explore because, unlike any other Garmin device I have ever owned, when you transfer a track to the XT, the custom icons for POIs and Waypoints don't transfer with the track. The only thing that comes through is a generic green square with a heart in it. That does me no good in marking water crossings, RR Crossings, Dangerous Trail features, Gas Stations, Bridges, or any other special feature I'd like to know to be looking for just from the icon type. As a result, I was forced to set up Explore, because those features get transferred as a part of a "collection" when a GPX file is sent to the XT and they are visible whenever the "collection" is visible. I wish Explore had the flexibility to turn on and off individual tracks within a collection, but currently that is not the case. Once a collection is visible, all tracks, waypoints, and POIs are visible. It's either all on, or all off...
Once I have the GPX file of my Track ready in basecamp, I export it to my desktop as a GPX file.
Then, I either Email it or Text it to myself.
Once on my phone, I open the GPX file. (When you do this, it's just a massive amount of text.)
Then, I use the Share button on my phone and share it with the Explore App on my phone.
It creates a "New Collection" in Explore (visible on the phone, or in the Web account via computer).
When my XT is near, and connected to my phone, the Garmin Drive App sends the "Collection" to my XT wirelessly.
You can then use the Explore App ( select "Where To?", and then "Explore" on the XT to View Waypoints, Individual Tracks, Routes, Activities, or Collections. It's here where I make the "Collection" visible, or not.
I also do one more thing, which is where the true beauty of the XT exists for me...
I convert each track to a "Trip" by selecting the "track", displaying it on screen and then using the wrench icon to "Convert to Trip". A Trip on the XT works like a "route" in that it provides spoken Turn-by-Turn guidance through my Cardo Packtalk Edge, whenever I am on a navigable road that my mapset knows. This is great when riding dual sport events where sections of off-road trail are connected by legal public roads. The XT will tell me when and where to turn to get to the next set of trail. Once off-road, spoken navigation stops and I simply follow the line on the screen while in the woods. Once I return to a known road on the "trip", spoken navigation resumes. To Navigate a Trip, you select "Apps" from the main XT Screen and then select 'Trip Planner" and then "Saved Trips" and then select the Trip you want to navigate.
I choose to have both the track (via the collection being visible), and the trip visible on screen, just to make sure that the trip doesn't deviate from the purposely created "track".
This process seems a bit convoluted and complex, but once you learn it, it's a really quick process that is all accomplished wirelessly, which for me is great, especially when attending dual sport and off-road events where sending GPX files between participants is super easy, so long as someone has it on their phone, either as an email or in a text.