I suspect that SMSL designs their products for the demand of their domestic market, which I don't believe exist much demand for HDMI and ARC (home theater is not a thing outside of North America).
I have been saying nonstop, these Chinese HiFi brands are designing their products for their domestic markets only and just make them dual voltage with minimal effort, so they can sell their products in other markets as well. International markets are an afterthought for these Chinese HiFi brands.
Sure, no home theaters outside of North America, rarely laughed so hard.
Home theater germany
In Germany and the EU there have been countless companies that have been building professional home cinemas for over 20 years, but that only accounts for a part. There are also many dealers and a large DIY scene. Just take a look through all the home cinema forums in Europe.
You are also way off the mark when it comes to the sales of manufacturers like Topping, SMSL (with Sabaj, Loxie), Gustard, etc. outside of China. There are countless small and large retailers worldwide, in addition to Apos, HiFi-Express, etc. Amazon provides storage spaces on site in Germany and the EU and also sells these products itself (Amazon/Amazon). Both of these only happen with products with high quantities and corresponding sales.
Incidentally, the sales of these companies in China only make up a small share of the local market for such devices.
No HDMI in China? Seriously? Where does this information come from?
China has approximately 450,000,000 households. According to statistics, depending on the province, 65 - 105 televisions per 100 households, i.e. around 360,000,000 televisions with HDMI. According to statistics, sales of HDMI cables are also among the highest in the world. If you have access to the statistics, you can easily check this.
The headphone market in the high-quality sector has increased extremely sharply worldwide, and with it also for DAPs, DACs and HPAs.
This is especially true wherever living space is scarce and expensive. This applies to all major cities/metropolises worldwide and has nothing to do with China.