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The Dynano engine family consists of small but powerful inline four and straight six engines with a high degree of parts commonality. Reflecting this design focus, all designs use direct acting overhead cam technology, resulting in a more compact engine than would be possible with more advanced overhead valve technologies. There are three main engine series:

C/Classic series: An inexpensive cast iron design for export and license production in developing nations, with a high degree of commonality with the pre-1980 P/Power and S/Sport series engines.
P/Power series: A design that balances power, cost, and fuel economy. In more modern engines, this means the omission of variable valve lift.
S/Sport series: The premier series of the Dynano engine family. Common features include the use of super fuel. More modern engines feature the full range of advanced technologies, including individual throttles for fuel injectors, variable valve timing, and variable valve lift. The series was discontinued between 1975 and 1990 due to the lack of super unleaded fuels.

I assume these engines are to be put into hatchbacks.

They are definitely for smaller vehicles. However, with more advanced head technology and/or a turbo, they could probably be developed into something capable of providing a vehicle with high performance, especially with how compact and lightweight they are. One issue with the head technology is how much it makes the engines sound like blenders at full power, so that alone might relegate it to smaller vehicles.

I do have a series of larger (1.3 to 1.5 liter inline four and 2.0 to 2.2 liter straight six) direct acting overhead cam engines designed, but for their later generations I might have them use a more modern head design. All the designs I'm currently working on are direct acting overhead cam throughout their different generations.

These could prove useful in larger motorcycles or even smaller marine applications

That's similar to the backstory I was thinking of for the company producing them, or I suppose marque (it's made by Dyna, my small/budget car company). In 1948 the company was hired to design a large inline four motorcycle engine, but then the company it designed them for decided not to purchase any. Fortunately, the engine turned out to be large enough for small automobiles, especially with its cam technology providing improved power relative to pushrod designs typical of the era. Although more advanced designs have been developed, the Dynano series is compact, has high power density, and is of a reliable and simple design.

I've experimented with the design in the engine designer, and with more advanced head technology the designs are capable of even higher outputs. There's definitely some promise for aftermarket parts and perhaps a factory race version.