from what i can tell about the mod it pretty much just provides the starting things needed to make it work.
i was wondering if there is any plans to add similar progression with the machines like in vanilla factorio, for example better space matter furnaces or if i need to look for a seperate mod that adds progression to spaceblock.
The mod is good and i like that almost every mod works just fine with it but i wouldnt mind if it had at least a little bit more content on its own.

Given the nature of attempting a broadly compatible mod, it is difficult to conceive of additional features that works consistently with the wide variety of mods available.

There are few distinctions that can be made between each logical stage of progression.
Even iron and copper are seen as identical to spaceblock, even though we know them to be substantially different.
Those differences that we might see must be applicable to all mods, and that is not an easy distinction to make.
Very open to suggestions here if you have them.

im aware that some mods change the value of resources but usually they also automatically re balance recipes from vanilla and other mods to match theres more accurately.
if they dont do that usually they either intend to match vanilla or to change the difficulty, so you you need to do is if your adding more to make sure it fits compared to vanilla and if it doesnt work out for a mod you can always just point out that if they rebalance resources that they also must make sure to adjust existing recipes and this is from a coding perspective the most easly to do anyways in a way that universally grabs all recipes and runs it through some calculation.
The only worry you should have is to make sure that newly added content doesnt introduce bugs in to the mod or make it any more difficult then it is currently to make other mods compatible with is.
If a mod is broken by the cost you defined for something thats entierly on them.
Also if you want to add just a little bit and keep the mod small you can simply just add more machines that are equalents to the vanila versions like it is with the Space Matter Furnace and whats already using vanila machines anyways like the assembler for example just let it also use all upgrades that exist for them.
Doing this should normally not have any impact on other mods but even being able to use electrical machines instead of burner ones is already a big deal even if there is no other mods used besides this one.

i understand your worries but i think your worrying over the wrong issue, you shouldnt be worried over mistakes other people do, as long as you dont introduce new issues to the mod and the new content fits in to what the mod already offers your perfectly fine to add as much or as little as you want to.

I meant coming up with new content for this is not trivial.

Best thing I can think of at the moment is a building that is like a chest but it sprays resources in an area around it and you have to place miners to collect the duplicates off the ground, like regular ore patches.
That might be fun?

if i understand you right that sounds like it wound generate an ore deposit in a predefined pattern with a random ore.
that could be fun, especially if you get rewarded for the challenge with lets say higher production rate then the current method for example.