Have you ever tried deconvolution? It's what BXT does, but doing it manually takes a bit of trial and error while learning the ropes. I did a quick comparison in PI in this thread:
https://www.astrobin.com/forum/c/astrophotography/deep-sky-processing-techniques/ai-in-processing/BXT isn't necessarily a must, but it is very helpful. The main advantage is the correctional feature and the ease of use (which can also be it's downfall when over-used/used "wrongly"). In my example I didn't really change much from the standard settings, as far as I can remember, but it does hold up as comparable IMO. Give that a go in Siril, I'm sure there are some tutorials on the matter if need be.
I don't know Siril specifically, but they do have deconvolution. I believe they also might have their own DBE tools for background extraction and possibly sharpening tools like wavelets and/or unsharpmask ? The latter two are often used alongside other tools in PI, BXT is not a one step solution as far as I'm concerned.