Dynamic Product Attributes

@GiorgosK you're right that Drupal Commerce still falls short in this context.

Even for smaller shops with attribute based products it's really really hard to manage them in comparison to many other eCommerce systems I know. Most of them have batch tools with filtering, selection and bulk generation built in.
Then this can be really useful and the concept @bojanz talked about in #3 can work well.

For other cases you may use order item types, which allow exposing configurable fields to the add to cart form (for example when configuring something like a plate and the user needs to enter the measures).
Drupal Commerce provides wonderful concepts to make all that possible, but my personal oppinion is that it still needs more out of the box features for better UX / SBX as people evaluating Drupal commerce get tired on the complex way and use other systems instead. Sometimes this also happens to me after > 15Y of Drupal experience. One example is the product variation generation from attributes above...

(No offence, this is open source and community job for all of us - I'm just telling what's my personal experience and opinion with the current state compared to the competitors and I very much hope to push things forward together!)

I'm working on an art e-commerce, and I have infinite aspect ratios.

It would be nice to have the option "Custom attribute" under "Element type", and then just have a text field to manually input the value when adding variations.