@cryptosam master, until you write, I would like to share a few of my experiences with your permission. If I have any wrong impressions, I hope those who know will correct me.
First, before making any evaluation regarding off-page SEO, we need to look at on-page SEO.
Single-page sites are generally for marketing a specific product or service. They aren’t really for sharing information like a blog. Since this is the case, the bounce rate tends to be a bit high. Google evaluates sites within their own field. Many sites similar to yours have high bounce rates. You cannot compare them with a movie site. At this point, first, you need to keep the user on the site longer.
How do we achieve this?
For example, if we open a review page about the product being sold and place it where the user can easily access it, the person visiting the site will stay longer. This could be like “ask a question” or, as I said, customer reviews.
We have improved the on-site bounce rate situation. Now the issue is creating content. There was a site shared recently.
I think cryptosam shared it. Find important keywords for the site there. Trust me, with this comprehensive keyword finder, words you wouldn’t think of will appear.
I once worked on a site about künefe. I thought the same way. “Man, what can be written or drawn about künefe?” Then over time, I learned that in such topics, there is always an attention-grabbing subject that can be written about. You will find content somehow. You will likely get about 2000 keywords in your hand. Select the ones with 3 or 3+ words from these. If it is a sector company, the right choice will instantly give you a place on the first page. Maybe you will have added a topic that won’t get much traffic, but a hit is a hit. And one hit pushes you forward.
By the way, one needs to pay some attention to the keyword ratio on the homepage. I once changed the theme. I switched to a single-page theme. I experienced a small fluctuation for a while. It happens a bit with theme changes, but this was a different kind of fluctuation. While examining it, I saw that my keyword ratio had dropped incredibly when I switched to the single-page theme.
In terms of content, just as an SEO-friendly article is written, we should design our homepage in that way. Whether it’s h1 tags, ratios, or bold text, one must always pay attention to these.
Let’s come to the code-to-text ratio.
In my opinion, it is an important criterion. I just looked at the code-to-text ratio of one of my single-page sites from this site:
http://tools.seochat.com/tools/code-to-text-ratio
Web Page Size :
51429 Bytes = 50 KB
Code Size :
36876 Bytes = 36 KB
Text Size :
14553 Bytes = 14 KB
Code to Text Ratio : 28.3 %
This ratio is 28 here, but when I look at Turkish tools, it shows over 40% 
How is the code-to-text ratio adjusted? Some say put text in the footer, but I don’t think it looks good. Prepare a proper article nicely, work on it for 3 days if necessary, around 500 words. Both your ratio will improve, and the time spent on the site will increase. You will get positive results.
I haven’t experienced the code-to-text ratio having a definite effect yet, but it is logically appropriate, and there are those who say they have experienced it.
Once the work inside the site is finished in this way, you can use many backlink acquisition methods.
There are forums, there are directories. But if the site is new and Google doesn’t trust your site much yet, definitely do not do these. There aren’t many people doing this job properly anyway. My words are for forum packages.
If you look in the forum, there was a topic like “how to do forum promotion”. I can help with this as follows. If you send me a spun article, I will make it unique and publish it on 50 forums for 10 liras. {I don’t make a profit from this by the way.} There will be a separate article in every forum, which will be useful. But I think the best thing is to open blogs. You said it’s hard to find content for the site anyway, so here is work for you
If you can’t find content for the site, open parallel sites for your own site. Write about similar topics. My approach on this matter is available on the forum.
To summarize briefly, the things I would write at length will actually end up in the same place. Don’t get backlinks before making your site worthy of receiving them. Adjust on-site titles, etc. Reduce bounce rate on the site. Open topics with long-tail keywords.
If I have any mistakes or shortcomings, may the masters correct them.
