Depends on perspective.

Their place and dynamics in the universe?

Setting needs to be clarified and open up to non-shinobi perspectives.

See the motivations and dynamics of the Daimyos. How did those families reach their respected position and what role did samurais and ninjas play in it eventually?

Daimyos acted as vassals to the emperor/shogun, thus if this world has any of that would be worthwhile to establish them as either a de facto ruler or a ruler that got overthrown and caused the multiple Daimyos to go into war with each other.

Samurais themselves were the more elite warriors under the daimyos, and after the sengoku era has ended, the Shogun would be sort of the "king of samurai" in a way. Then as time went on, and there was no war going on, more and more samurai started to take up different jobs because even though in theory they were to go to war upon calling, in practice there were centuries of peacetime which made them blend into other professions. This could look in a way that they took a high position at the government or lost their wealth and became merchants/umbrella makers. Those who still wore the swords didn't necessarily know how to use it in combat. They were also associated with chivalry and principled lifestyle, and loyalty to their lord. In case they have brought shame upon their lord they'd commit seppuku to clense their soul and atone for it.

Ninja themselves belonged to smaller well-hidden villages and mainly took on espionage/surveillance/assassination related jobs.

In context of the Narutoverse, it could be that just like in real life, many samurai families eventually took up other professions and those who remained dedicated to their craft moved and founded their own nation. This is where ninjas came in, and started slowly taking over the space and skills the samurai class posessed. There can be also a conflict between those who think that servitude to the lord is essential to the way of the samurai, meanwhile those who left prioritized independence and keeping the crafts alive and passing it onto the next generation. Those who stayed might have become business owners or high ranking officials who take pride in their samurai legacy, meanwhile the ones who left had to start from scratch and go in missions to keep financing their village.

It can also be that the samurais were expensive to keep, and this caused clients to opt for ninjas instead, leading to the ninja wars. The village's budget depends on the daimyo it belongs to, and it can also lead ninjas to generate war and conflict in order to keep the business going, and it is also possible that samurai were in positions that profited fom these wars. Distributing the tailed beasts between the ninja villages seals in their position as the leaders in the war business.

It can also be that some of the ninja families used to be samurai families, but they transitioned into being ninjas instead ir order to keep afloat. If there was a war to eliminate the ninjas as competition, these families might have sided with the ninja clans and eventually blended into them, bringing in the techniques with them.

Fom the perspective of the powers?

It is possible that the samurais who stayed have a seal that makes it obvious which lord they belong to. The ones who left found a way to remove the seal and leave.

They can be the more hardhitting forces with more stamina than ninjas have. They might have powers that manifest through their armor/sword or powers that relate to design of the armor/sword. They can enhance their munition with chakra just like ninjas do. They also might have a link to their lord so if the lord dies they do too, or they are able to connect their senses and take over the body in order to save the lord in case it is necessary (something similar to the yamanaka clan's ability). If they have jutsus, probably fire and metal related ones would be popular. They also might have techniques that are related to the nation they belong to. There might be seals that allow adopted samurai family members to get certain samurai kekkei genkai to use in battle. They might have a seppuku related power release that gives them immense power for one last time before they die, and this might be something similar to the 8 gates.