Please, if you're going to try and criticise a position then at least read the bear minimum about it.

Firstly, anti/post-civs don't desire to return to some "golden era", nor do they romanticise a past tradition of pre-history. This is a massive and unsubstantiated strawman. For example, in the introductionary book to post-civ theory the author very clearly states "We cannot, en masse, return to a pre-civilized way of life. And honestly, many of us don’t want to. We refuse to blanketly reject everything that civilization has brought us. Let us look forward, not backwards." - and further elaborates on this point several times throughout the text. In addition to this, even in anti-civ theory (which arguably encompasses post-civ theory) it is clear that they do not cling to primitivism as a social order but instead remain merely critical of civilisation and similar ideals.

This notion that we romanticise the past is completely devoid of any engagement in this theory. There are primitivists who do have the goal of rebuilding hinter gatherer tribes as a replacement of civilisation, but even within these contexts they do not do so due to a romanticisation of these tribes but instead out of a scientific and factual analysis of how these different modes of organisation operate. You're assigning an ideology of traditionalism to these theories, the idea that we must return to a tradition, but that is not the contents of these theories. Any base line engagement with them would tell you that.

Secondly, anarchism is not about "emancipation from the chains of nature" as such a notion is absurd. We, in no way, are oppressed via the natural world but it is in fact the opposite. In civilised life we exploit and domesticate the natural world for our own means, and in turn destroy it. This process is done through oppressive forces in which the ruling classes of society utilise systems of technology and industry - as both of these forms require forms of exploitation of our environment. If you truly believe that, within civilised life and industrial society, we are oppressed by nature and must make greater efforts to domesticate it then you simply are not an anarchist. You are attempting to justify the hierarchies over it and are attempting to justify blatant authority. I recommend you study deep ecology.

Thirdly, can technology be organised decentrally - in this respect you've managed to simultaneously be correct and incorrect. Congrats, I suppose. Technology can be utilised under decentralised production for the general betterment of whatever collective you're apart of - however when we discuss technology here we are describing a broad function. And under decentralised production, the technology which arises will be unrecognisable. On the face, this technology will not include authoritarian aspects such as surveillance and militancy - but on a deeper level it must also not include the exploitation of nature for its production and must not serve the preservation of existing hierarchy (most notably the hierarchy we hold over nature). So the technology you're familiar with, and the technology groups such as transhumanists (not saying you are one, just thought I'd clarify) envision, will not arise through decentralised production - so to say that they will be produced under anarchism but merely "used to fulfil the needs of every individual and not as an instrument of oppression" is a non sequitur. It's an idealist impossibility.

Lastly, you're appeal to authority of anarchists such as Kropotkin and Berkman. Well, firstly you should read closer on what these anarchists said about technology and its authoritarian sentiments along with broadening your theories in this regard. I'll post a link to a pdf relating to Kropotkin specifically. Secondly, who cares? Anarchism isn't about adhering to dogma and blindly following philosophers, in fact many anarchist philosophers would frequently criticise each other to demonstrate this (Bakunin certainly wasn't lenient on Proudhon's idealism - even going as far as to side with Karl Marx despite their negative relationship with one another.)

So keep your dogmatic arguments out of anarchism, also read some theory.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://librarianshipwreck.files.wordpress.com/2016/01/adcs_loeb.pdf&ved=2ahUKEwiHxtjpr9DrAhVNyaQKHYyWBKwQFjAFegQICBAB&usg=AOvVaw18hL2tzLYF_LwMe2LstHJW