GS is just an automated web scraping and search engine service. It can't be picky the way WP is. If you use the necessary <meta> tags (which can be auto-generated from the existing user+title metadata), it's unclear why it wouldn't be picked up by GS eventually.

Serendipitously, I added those <meta> tags to gwern.net just last week after a Twitter discussion about how and whether to get DOIs. At least in theory, I shouldn't need to get DOIs to get better visibility, but as a backup, I also registered a GS profile which may or may not let me enter pages manually. In my experience, GS updates quite slowly (I think because GS seems to be a skeleton crew passion project and not integrated into regular Google Search), so we'll see in a few months if any of this did any good.

As far as WP goes, I'm not sure what can be done. As a group blog anyone can post to, being a LW post can never confer any particular notability or RSness on its own. It has to be a case by case basis. Given the ever more deletionist approach of remaining WP editors, that will be difficult even for cases where a LW post is a very good writeup on something and would make an excellent External Link addition, unless it is something like an official statement or interview etc. (Obviously, if a MIRI staffer posts an official piece of MIRI news, there would be no problem citing it in the MIRI article. Stuff like that.) Wikipedians crave status, and so the best way really is to somehow promote pieces into formal publications in somewhere (anywhere) Peer-Reviewed™ and treat a LW post as a preprint.