1 Pager vs 1 Pager + Blog

My competitor has a 1-page website, basically, it's just a homepage with like 7000 words in it.

I made better texts, did good on-page SEO and now I'm building better links.

Do you think I have better chances if I start buying like ~3000 words articles on the general topic of the website and add something like a Blog? Not for the people of course, but for Google, since in my niche, there are 0 ways to drive traffic from articles to a money page.

I was thinking maybe it would give my website more weight.

Yes, adding content around the topic of your site helps. I'd try to rank for some keywords with volume, and make it good enough where people stick around for a while. If you can get some traffic and good bounce rate on those pages, then that's a good sign to Google. Make them whatever length is appropriate for that keyword, not just always ~3000 words.

articles can drive traffic.

write for question based articles and solve people's pain points, and slightly promote your money page in your articles.

general content does little help.