Bluetooth transmitter in 3.5mm. How to connect BT headphones to devices without BT support?

Question

Bluetooth

The problem is very common, I want to watch a movie at a normal volume, without waiting for the household.
What we have:
Headset - Parrot Zik
Source - Dune Smart B1
Question - how to connect?
There are a lot of identical transmitters for $ 10 on dealership, ali and other eBays (I ordered one of these, it will arrive soon). But their problem is in single-mode operation (either charging or broadcasting), and in general they are confused by their quality and appearance. It is very strange that we do not have such devices at all, even from decent manufacturers.
Therefore, I want a device:
1. Does not require a separate charge
2. Supports all the necessary standards for stereo broadcasting
3. Availability in the Russian Federation (desirable) How did you
solve a similar problem?
Z.Y. As an option, I'm ready to change the player to something with bluetooth (but not a computer). The only requirement is the ability to play mkv up to 30Gb over the network without brakes

Answer 1

I found a solution that matches the description.
I think, isn't it easier to change the dune to an android player ...

Answer 2

hmm, maybe it's better to change the headset to regular radio headphones like good shanheisers. They keep batteries for a very long time, the sound quality will be better than bluetooth ...