Bunny Bonding - Next Steps?

I haven't posted on this forum in awhile mainly because I've had no problems with my bunny more or less. So here is what's happening now:

I have a bunny, 4 years old, lop, male, neutered awhile ago (over 1 year ago) not super social, doesn't love people but tolerates them. I thought to see how he owuld like a friend. One time, I brought him to my friend's rabbit to see how he would take to another bun, she had a neutered male as well. We gently put them together and they ignored eachother then even sat together in a litter box and had no problems whatsoever. Anyway, that gave me a good sign that he may want a friend. So I have been looking for fixed buns that are around his age. I recently got a bunny from a lady looking to rehome her 6 year old neutered male. Now I know male male bonds aren't ideal but I figured I would give it a try. Here is what has happened so far.

I made a two separate pens beside eachother with a pool noodle between the fences so they can't fight through the bars, but my bun in one and the new bun in the other. This is in a neutral space so it's new to both buns. SO far, the first night, they sniffed through the bars but mainly just ignored eachother, and both used their litter boxes very well.

This morning I swapped them into eachother's pens and similarly no problems. No fighting, no marking, they use the boxes and just kind of hop around without seeming to interested in eachother.

Now I don't know waht to do next, I was planning on continuing like this for a week or two then trying some supervised play time? It seems to be working so far and I don't want to jeopardize anything at this point as I think this bun is a reasonable fit from what I have seen.

Any advice or tips would be appreciated. Thank-you!

I would try SUPERFVISED "play" in another neutral area away from their cages. And perhaps a stress bonding session in a carrier in the car or something.

Yeah, try to put them together in a neutral small space where they can't go in corners you can't reach or corner each other. Of course, you put food with them. Like things they really like and which will keep them occupied for a while (carrot / parsnip are always winners, or a big appletree branch if you've got a garden...). Keep a spray bottle with you so you can separate them without getting mauled if it doesn't go well.
If everything goes well, you'll be able to put them back together in their definitive set-up (cleaned thoroughly with vinegar to remove smells) at the same time.
I never used stress bonding. It might be useful if the normal introductions fail, I don't know. I really shy from stressing my rabbits if it's not absolutely necessary, but maybe that's just me ^^.