So, the continuation of my epic with gluing a magnetic ring.  After analyzing the forums about osmo mobile 4, I did not find anything useful, maybe a few one bother with this ring.  By the way, the new model osmo mobile 4 se is not equipped with this ring, apparently the problem with its fastening has not been finally solved.  And so what I found.  The key to this procedure is the Primer for applying adhesive to the glass surface.  It is used in construction for gluing to a glass surface, I used napkins soaked with this tool, ordered for aliexpress here:
US $ 0.43 29% DISCOUNT |  20 pcs, primer 3M 94, tape adhesive
https://a.aliexpress.com/_mNV2rV0
  The technology is as follows:
We clean the surface and process with Primer
We wait 5 minutes until it dries completely (this product may dry out faster, it smells like it is something on acetone).
After that, we glue a 3M sticker, and on it a magnetic ring (I also processed the sticker with a Primer).
We are waiting for 72 hours !!!
As a result, I managed to detach the smartphone with a magnetic ring from osmo mobile 4, how long this design will last - we'll see.
Yes, since I spoiled the magnetic ring that was included in the kit, I ordered it separately (the support service sent me a paste-like sticker for restoring the magnetic ring for free via DHL, for which they are very grateful, but I already managed to order a new one).  I note that I do not regret this order, firstly, the ring itself is fixed at 90 °, the complete one rotates freely, and secondly, the template has a small area with glue, which is very convenient when marking the mount.

So, the continuation of my epic with gluing a magnetic ring.  After analyzing the forums about osmo mobile 4, I did not find anything useful, maybe a few one bother with this ring.  By the way, the new model osmo mobile 4 se is not equipped with this ring, apparently the problem with its fastening has not been finally solved.  And so what I found.  The key to this procedure is the Primer for applying adhesive to the glass surface.  It is used in construction for gluing to a glass surface, I used napkins soaked with this tool, ordered for aliexpress here:
US $ 0.43 29% DISCOUNT |  20 pcs, primer 3M 94, tape adhesive
https://a.aliexpress.com/_mNV2rV0
  The technology is as follows:
We clean the surface and process with Primer
We wait 5 minutes until it dries completely (this product may dry out faster, it smells like it is something on acetone).
After that, we glue a 3M sticker, and on it a magnetic ring (I also processed the sticker with a Primer).
We are waiting for 72 hours !!!
As a result, I managed to detach the smartphone with a magnetic ring from osmo mobile 4, how long this design will last - we'll see.
Yes, since I spoiled the magnetic ring that was included in the kit, I ordered it separately (the support service sent me a paste-like sticker for restoring the magnetic ring for free via DHL, for which they are very grateful, but I already managed to order a new one).  I note that I do not regret this order, firstly, the ring itself is fixed at 90 °, the complete one rotates freely, and secondly, the template has a small area with glue, which is very convenient when marking the mount.