>targeting many, if not most
Not really. Barely a handful out of 54 minority groups that accounts for ~2% of the population. Most are left alone because most of minorities are already sinicized and "compatible" with broader Chinese society.
> ultimate motivations
This is really simple confluence of two major policy changes.
1. New minority policy, no more minority privileges like family planning exemptions from 2 child policy. Particular focus on mandarin fluency to integrate into broader society. Uyghur, Tibet, Mongolia etc, this is important because 99% of China operates on Mandarin, those who aren't fluent gets left behind. Above minority populations also have large rural populations whose lifestyles (agrarian, herding etc) are being phased out due to new land use policies regarding agriculture (food security). Which means urbanization, so there's also a lot of rural-urban labour transfer programs to up train people, i.e. the entire vocational training west portray as slave labour has been regular program in many provinces for at least 10 years for millions of rural Han.
2. New religion policy, rather _A_ religion policy. There simply was never a proper framework for regulating religion post CCP, leading to all sorts of drama. Not just in terms of prosecution, but illegal temples and other unregulated schemes. Lot's of tomfoolery in explosive growth of Chinese buddhism. Essentially, regulate religion, religion must have Chinese characteristics and conform to socialism.
Not new policy, always relevant.
3. Groups that participate in 3 evils, separatism, terrorism, religious extremism get stomped: Uyghurs, Tibetans, HK, Taiwan when that comes around.
Basically, stop 3 evils, spread mandarin, control religion, vocational training for ultimate development goal: urbanization and better rural land use. This is inevitable byproduct of Chinese population size + land constraints. Mix and match interventions, if you're a very religious, rural Uyghur who speaks no mandarin and have no employable skills, you get everything. If you're a Tibetan herder, you get some mandarin lessons and vocation training. If you're a Mongolia urbnite, make sure your kids know mandarin.