For me the most important part of preparing for cycling in Latin America was learning conversational Spanish. I spent about 2 months studying in Panama to get a basic handle of the language, just going to school in the mornings and hanging out in local spaces in the afternoons where I could hear colloquial usage. Even though it's possible to get by traveling in other countries by miming your requests and using translation apps, it is much easier to reassure locals that you really are looking for a practical cycle route and not some kind of touristic detour if you can speak enough of the language they figure you're not going to collapse in a heap as soon as you can't find a McDonalds.

In Panama I just rented bikes and did day trips. In Colombia I started doing that, then bought a bike once I realized the country was a better fit for how I wanted to travel. It seemed like there was a stronger bike culture there. By which I mean, there were relatively more utility cyclists - not sport/fitness cyclists, but people with baskets on the back hauling fish or produce from their angling spot or farm to the market. Aside from bicycles, a lot of locals also rode scooters or light motorcycles - this made me feel more confident on the roads because the ubiquitous trucks and buses were more used to sharing the road with smaller and slower vehicles.

The big difference I found touring in Colombia versus the US and Canada is that towns with affordable accommodation and other services were generally much closer together. It wasn't uncommon for me in parts of Canada to have 100km between towns, without even a guarantee to find a grocery store much less a camp site or motel in the next place. Especially in the prairies it was necessary to carry a LOT of water, plus plenty of food like oats, nuts, tortillas and so on. In Colombia there are lots of small towns of under 20,000 people and they all have hospedajes (kind of like a European pension, or very low budget B&B-without-the-breakfast), bakeries and convenience stores. I barely even needed a food bag - every day I could get fresh pastries in the morning.

Because the towns were close together, I took it easy and sometimes rode just 40km or 60km a day, which was well worth it because the temperature in some areas was around 36C - the kind of heat above which you really start feeling heat stroke after 2-3 hours on unshaded roads. To deal with the heat, I decided to pull over everywhere there was a roadside stall selling drinks. Usually it's fruit juice (watermelon is best), sometimes a lemonade made with panela, occasionally chicha. I figured anything with water and sugar was worth stopping for.

To navigate I just used the standard combination of OsmAnd~ (OpenStreetMap) and BRouter tool for offline routing. But it's important to double-check on Google Street View when you have internet, because often the helpful bike routing tools avoid the highway, which actually in Colombia is what you don't always want to do, because the "highway" is sometimes just a reasonably quiet two-lane country road. On the other hand, some of the back roads look like well-maintained gravel, but due to heavy rain they can turn into very deep mud. I got stuck in one or two spots that looked okay on Google Street View but were a real adventure on the day - not even a car could make it through, horses and dirtbikes only. But the benefit of being on a bike is you could easily head down a back way and then cross the river on a small sampan designed for foot traffic, so sometimes taking those back roads paid off for the fun aspect. They were definitely the exception rather than the rule, though - most times I figured better safe than sorry and tried to stick to main roads, especially when a back road would require more than 50km (my theoretical limit for being able to walk/hike back out in case I had to abandon my bike).

One thing I didn't do in Colombia was go deep into the Andes. The climbs are just ridiculous. Like 2000m or more. Personally I don't enjoy hill climbing, and I don't like cold temperatures, so when I am touring on bike I do everything I can to stick to the lowland and plains. I think going the hills would be a very different experience and might need different preparation. Although, I think the hills are also far more popular routes both for bike tourers and for sport/fitness cyclists, so there would probably be much better support. Down in the valleys you're going to find yourself cycling with campesinos and trying to get stuff fixed at a moped shop instead of a bicycle shop, but that was fine by me.

I think the best way to go if you have the time is just head over to the country you're thinking of traveling in with some panniers rolled up in a duffel, rent a bike once or twice to see if it feels good, then buy a cheap bike when you're there. That way you haven't invested too much in some kind of "dream journey" that doesn't turn out to be what you expected. But perhaps that's just my way of travel, not for everyone.