>>999
The first part of feeling what it's like to be a tree, a rock etc is something I used to do in the beginning. The following steps doesn't lead to the same thing as the mula bandha at all, even if useful.

The mulas when performed added in sequence forms a powerful sadhana (routine) which doesn't actually require any special awareness. It relies on a series of muscle contractions synced with breathing and isometric contractions to be held independent of breathing. This leads to being able to isolate the right position and then maintaining this in meditation.

At an advanced level the effect can lead to a silent ecstacy stronger than drugs, as the energy increases. Without proper self control this build-up is probably not possible as you would release the energy based on desire to "feel" more. What you use the energy for is up to you, it's merely transformative. I personally end up creating internal "stars" and moon orbs circulating them, representations of concentrated refined energy.

>there are steps to do with a partner too if you have access to one
I would not do this with someone who doesn't already have an awakened and well developed kundalini. Spiritual entities cannot come into contact with you unless their level of purity matches your own, so that is less of a problem, but humans can be dirty to any degree.
During the paired version of practice above, the snake's head will sync with her genitals and the split tongue of the snake will enter your body. Each of the tips will rest on each of your testicles, this forms a highly integrated energy flow. The snake, being a living entity will know to do this if advanced enough.
The experience of this can be rather physically awkward and create unease despite the process not taking place in physical 3D.
You can ask yourself how much you would need to trust someone to perform this practice.

The founder of buddhism is quoted to have said that "a monk who cannot stay away from women should rather fuck the mouth of a snake". This has been interpreted literally, but perhaps he was telling them to instead practice tantrism?