Little pine seedling “weed”

Hello all, I’m a beginner but have been voracious in my online education, attending local shows and meetings, and spending some time with Jonas at one of his in-person weekend sessions. One bonsai I have is a large lava rock slab with a boxwood and cotoneaster growing on it with most of the growing medium covered in a nice moss carpet. I weed the moss frequently from oxalis and other tiny weeds but recently found a pine seedling growing. All three plants are doing well and since I’ve been meaning to add a pine bonsai to my small but growing collection I’m elated one has sprouted all by itself. It was fate! Haha. Now I’m wondering how long I should let it grow where it is, or will I have issues later with roots entwined with the boxwood possibly causing problems with both of them? Since it’s doing good I’m hesitant to move it or transplant it as I imagine when young like this they can be fragile or temperamental to transplanting.

Any advice? Leave as is for now? When should I transplant (both at what age and time of year)? Any how any clue to which pine species/type it might be? And lastly how does it look to you? Healthy? It’s recently developed that brownish webbing at the crown, is that normal? Thanks for the advice. Photos attached.

I’d say keep it if you want a pine in this composition to grow where this one happened to sprout. if you want it somewhere else or would like to develop it on it’s own for now (this would be the easier approach), you can remove it and plant in another container when the weather cools a bit (January). Am curious what kind of pine it is.

As for the brown bits, it looks like caterpillar damage. Nothing to do about it now, but keep on the lookout for caterpillars in the garden!