These are individual characters that cannot be easily typed as they are enclosed in a circle and, as noted in the blog post, only included in some character sets for a limited time.
Most commonly they are typed as a circle followed by the character as in ○ビ and ○金 (used in my blog post) or enclosed in brackets to approximate a circle as in（金）and（ビ）or you can type unicode joining character to have the characters overlap each other as at https://ja.wikipedia.org/wiki/囲み文字#仮名文字
This is somewhat related to the paragraph about Wikipedia that I put in the blog post. 1984 was very pre-internet and this stuff only happened in Japan. So, there are many references to Maru-kin ○金 and Maru-bi ○ビ in the book, and on the internet, and they're mentioned on Japanese wikipedia. But whether or not there's enough quality citations from verifiable sources to please English Wiktionary or Wikipedia is a battle I simply don't have the energy to get into these days. I'd encourage you to ask any sufficiently old Japanese person and they will let you know all about this era, and then gather enough quality cites.
Because it's a Japanese-specific phenomenon (isn't it ?), and I would expect that different language Wikipedias copy from each other all the time, so if your goal was to (as I assumed it to) to put that information on (at least) the English Wikipedia, then having it first featured on the Japanese one would give it much more weight ?
Emoji is of Japanese origin but absolutely a worldwide phenomenon at this point!?! Of course this new info should be on all wikis, but I don't think it matters at all which one comes first. I don't edit Wikipedia, so I don't have any skin in the game.
> 渡辺和博の『金魂巻』で、「丸金」（㊎、金持ち）と「丸ビ」（ビ⃝、貧乏）が使用され、これは流行語大賞を受賞した。
They mean rich and poor