I’m sorry, I should’ve been more clear in my response. The Chinese-owned “Silver Reed” company still makes the SK280 and the SK840 machines that were designed by the now defunct Japanese company back in the 80-90s. These are the machines sold in stores. Some people believe they are of inferior quality when compared to identical models of [used] machines manufactured in Japan. And quite often (depending on your location) you could find non-used or slightly used examples for less money. However, old machines have to be re-oiled (since the oil has oxidised long ago), and have the “sponge bar” replaced (polyurethane foam is likely to be disintegrated, too). Personally, I have no opinion on “Chinese vs Japanese”, since I’ve once played with different models of Passap (also known as Pfaff).

But yes, it’s somewhat eerie to observe women (it’s mostly them who enjoy knitting) discussing what kind of model to buy, and having absolutely no clue that the knitting machine age is over.

As for the sewing machines, I think that the best option for any domestic user is to buy a vintage sewing machine. Models made in the 1960s and earlier typically don’t have nylon gears and don’t tend to go out of alignment if you happen to hit a sewing pin with a needle.

One particular resource (that I know of) that offers detailed information about the sewing machine internals is https://www.naehmaschinenverzeichnis.de/

If you’re in the US, the models to look for are 4×× and 6×× series Singers, although there are tons of different options. The German-made Singer 401G in particular is considered the Holy Grail of vintage sewing machines because it’s a free-arm machine (only common in Europe since ~40–50s, not common in the US till the 1980s), has almost all the functions a domestic user may need, and has no plastic gears.

However, pre-1980s sewing machines have one huge disadvantage: they all had a [resistive] rheostat foot controller, which made maintaining low RRM practically impossible. The ones that came with a Triac in the late 70s and early 80s sometimes boasted the word “Electronic” somewhere on the case (this is the case with some Berninas, like the 830). If the machine doesn't come with a Triac foot controller, it’s best to adapt a modern one or do one yourself.

Other options are:
1) To replace the motor with a servo,
2) To add an RPM-control (PID ro ARDC) circuit (either with or without the encoder). One Back-EMF based example with Dremel-like tools is https://hackaday.io/project/166492-grinder-speed-control-wit.... But it doesn't apply to sewing machines well enough, since it’s difficult to determine very low RPMs needed in sewing.
3) Use pulleys, if you’re willing to sacrifice high sewing speed https://www.youtube.com/watch?v=qKDSaNmB0rs

I do believe that some modern brands like Bernina and Pfaff make some advances, however I feel like most of them are related to quilting/embroidery, and not sewing. For example, there are no modern domestic sewing machines (besides the Sailrite) that can comfortably sew thick leather. Modern machines also have no real option for mechanical adjustment of presser foot pressure (important when you deal with vastly different thicknesses of materials).