So I use a generator that I've built filled with prompts collected from books and community posts. I've got all of these broken down into categories. Theres a few for combat at varying levels of difficulty, and those include some where the combat is already over, and the parry can talk to the winners or aid the losers, or about to start and the party could possibly intervene to prevent it.

Other prompts include foliage, beautiful sights, landmarks, historical events, npcs, whatever your players are likely to be interested in. You got a druid? Plants and animals. Bards or other social characters? You need travelers to meet. It's all about knowing what hooks your party will bite on.

So let's say you have a list of 8 things that are happening between the two points of travel. You need a meaningful way for the party to choose what they want to interact with. You could draw a small hexmap of the area and put a reference for each interaction on it asking them to move a token as they decide to travel. Or you can consolidate to a few paths and group your prompts along each one. Here's an example:

"You stand at the top of a high hill and survey the area ahead of you. There appear to to be two paths forward, the one on the left has recent wheel tracks from a wagon that looks like it was weighed down with cargo (this signals that merchants or refugees came through here), it leads into a forest with a dense canopy that covers the valley ahead. It looks like there is a clearly as the earth slopes up the far side (maybe there's a lake, or a small village, just a cabin, the site of an ancient battle or a hill dwarf logging operation.

The other path heads towards the mountains, it looks like it's going to involve some climbing (now the parry knows there are skill challenges this way), you can see some sort of altar or shrine on one of the lower cliffs that glitters with precious metals (do they seek treasure, is there a cleric or paladin in the party?). There are footprints here, but they are faded, no one has gone this way in a while (this means I've grouped the harder combat encounters here too)".

The key here is not just asking them to choose arbitrarily, but to inform them of what's coming and give them a chance to chose what they want to do. Both paths will lead to the same place but have very different experiences on the road.

I've gotten pretty wordy already so I'll stop here, but if you want to go into more detail about building roadside encounters, I'd love to.

I started my current campaign with absolutely no plot in mind. I chose characters and players I liked and gave them a campaign long escort quest of an author that needed to travel and see remote places and customs to write about. So these kinds of encounters are a huge party of my game.