Here is another take on the nimitta phenomenon and jhana states, from Mind Illuminated by Culadasa

I haven't been able to reach the jhanic states through meditation only, though I've seen the nimitta rise. However, I have had a few psychedelic experiences where I've entered a state of bliss with calm consciousness.

I haven't had a DMT breakthrough experience for approximately a year, but I keep going back to one experience where I remember quite clearly the onset. I first saw like an old CRT television screen with noise, the image was quite dim, but then I surrendered to this image and it took over, opened up like a portal and I went to the other side.

The breakthrough experiences haven't of course been very stable concentrated states of mind, since there is usually very much going on. However, I've gotten into the states that resemble the jhana states with ayahuasca (once combined with LSD) and psilocybin at least once or twice and the first time the experience was very stable. There had been intensive preparation and quite optimal conditions with a cottage in the middle of snowy landscape and two very trusted friends.

I'm looking forward to developing these states both through meditation only and meditation supplemented with psychedelics.

So far, when going on psychedelic journeys, there has been so much "content" related to the issues that need working on in my personal life that the situations have been few where I have just been able to calm my mind and focus on being here and now. I hope to be able to work both on the level of content and level of beyond content. It's just very easy to get caught up in thoughts and forget about the possibility of letting go.

I believe that the maps provided by Culadasa and Daniel Ingram can help navigate the psychedelic spaces too and cultivate the inner worlds that they open.