I’ve read (sorry, I forget where) that Navalny was diabetic and a drug user as well. Further, he likely received the clot shot + boosters while in Germany. So it’s not at all inconceivable that he died of natural causes and his own poor choices. But if he was murdered . . . Considering the PR value of his death while in custody — very negative for Russia and over-the-top positive for Western neocons — it’s far more believable that he was killed by his CIA handlers than by Putin.
The CIA had the motive, and they were in tight with his Mother and Wife who stood to be showered with cash should the US Government Insurance on Navalny's Life not be as advertised.
The Wife visited Navalny and delivered (CIA?) "medicine" to him the day before he "mysteriously" died.
VERY Interesting, as Navalny was worth more Dead than Alive.