I don't see Yogacara, or any Buddhist thought, as subjective monist idealism. That would imply a 'true' state of affairs (transcendental unity) and a false state (various manifestations). Buddhist thought expresses non-duality between these, and other dichotomies, probably best illustrated by Indra's Net: all are in one, and one is in all. The idea of the Dharmakaya might seem to fit the idea of a transcendent unified subject, but it very definitely does not have subjectivity, and is 'non assertive'. I would look to the way Godel-Incompleteness shows that for actual minds there is always space for the previously inconceivable (part of the definition of the Dharmakaya), for self-transcendence not only of self, but of unity, of emptiness, of all concepts, and even beyond concepts, which are intrinsically limiting. This article gives an accessible description of how Nagarjuna expresses this, and of how we can relate it to 'mind-like' quality of open-ness we can call being a 'strange loop'.
I like subjective monistic idealism. But I would argue for it on a practical psychological basis, rather than a transcendental one. Looking at Wittgenstein's Private Language argument, we see how the self can only arise as tool, in communion with and reflection of others. We develop mirror neurons, which help us copy the movements of other bodies, and mentally project ourselves. We develop theory-of mind in relation to our social groups (defined by the Dunbar number, social group size strongly correlates to brain size), and our prefrontal cortex develops to enhance our ability to respond to that.
Then, consider Rawl's theory of justice. Why is this idea of universal body-swapping, a quite outlandish idea, so compelling that it seems to strongly correlate with our intuitions about justice? I would argue because mirror neurons and a more primitive concept of self founded in projection into the bodies of others, predate and are a precondition for our social self to develop. Projecting ourselves into the situation of others is an essential precursor to the development of language, and intelligence.
I'd go further, and contrast this mode of intelligence development in social animals, that fits the Dunbar number social-group to brain-size correlation, with the exceptions. Birds and squid/octopus seem to have developed intelligence more squarely focused on problem-solving. Octopuses are able to figure out complex problems like unlocking a box with a key, but seem to largely forget what they learn. They seem to have very flexible brains, but limited persistence of self - they are barely social at all. Birds seem to have more advanced independent tool use than any ape (although apes can mimic spear fishing and fire lighting). They can make logical inferences at least as well as apes can, and are perhaps capable of more complex mathematics (the only animal shown to do division calculations is a parrot). Some birds like ravens have done this despite small social groups or being nearly entirely solitary. I would say human intelligence is almost entirely reliant on tools developed for insight into the minds of others, and has a strong tendency to be able to best assemble information into 'characters' or 'identities', because that's what our brains evolved to do. There are indications the Australian aborigine 'dreamtime' stories may encode detailed accounts of volcanic eruptions many thousands of years ago - possibly among the oldest human records, and the Irish Tuatha Ne Danaan long thought of as just 'fairy stories' actually told the stories of the land and harvests, gathering information in a way that could be remembered (but took initiation to decode). Greek mythology seems to be a complex psychological map, as explored by Jung and others, which I would relate to their culture's focus on how to 'amp up' mythological stories for competative plays. It is again about giving 'identities' to principles, and lessons being stories of interactions, as though they were people.
From a physics perspective, it is interesting to note we have no access to information that hasn't been filtered through a subjective experience. We do a lot of comparing and contrasting, seeking consilience, to account for that. But consider, time may be a result of subjectivity. An emergent experience, out of everything being 'now', that allows us to make sense of a complex higher dimensional shape passing through the 4D 'plane' of our own experience. This would reconcile the arrow of time, which is what we experience, with time as a dimension (General Relativity) and the fundamental reversability of every law of physics (Quantum Field Theory). In this sense subjectivity may not be fundamental, but without it nearly everything we think we know about causality fails, or at least is revealed as a tiny part of a far grander and more complex picture.
The other tack that can be taken is as I mentioned earlier, that Godel-Incompleteness implies the universe has a mind-like 'strange loop' character. But, it doesn't imply any transcendental subjective unity though. Consider that our own sense that we are unified breaks down under analysis, split-brain observations, multi-agent mind models, and the work-space model of consciousness. So I would say this implies a kind of animism, the universe is thoughts, rather than pantheism, the world is the mind of god.
