Bitcoin had several hard forks in the past. The dominant version based on market cap is also referred to as Bitcoin Core. In order to function any decentralized software must depend in some proportion of centralized resources.
The official domain is bitcoin.org, currently registered on Namecheap. It was initially registered by Satoshi Nakamoto but currently it’s owned and managed by an unknown person going by the name “Cobra”. By using github.com as a communication channel, the owner of the domain manages to keep it’s anonymity. All site changes are done based on pull requests from the community. In 2020 Cobra has announced he will give up the ownership of the domain.
There are two organizations mentioned on the website as sponsors: BitcoinFoundation ( headquarters in Washington, D.C.) and paxful.com. After some turmoil over the years the BitcoinFoundation doesn’t have much activity anymore.
Bitcoin Core Software Seed DNS
Pieter Wuille(Belgium) is the co-founder of Blockstream and a top Bitcoin core developer. His name appears in Bitcoin core software near one of the DNS seeds, required by new Bitcoin nodes to discover the Bitcoins pears in the network. Currently you can check the github repository for dnsseed to find the devs helping to provide this DNS resources.
Reddit is a very popular place to talk about cryptocurrencies. The main subreddit channel for bitcoin core is /r/Bitcoin and the list of moderators is publicly available. You would expect the top moderators (by age) to be trustworthy individuals but when you look at their profile you might be surprised by the other subreddits managed by him.
The Twitter handle mentioned by Coingecko /btc has a reference to btctimes.com. A bit of wrongful promotion maybe?
The Bitcoin Facebook community probably associated with Bitcoin Foundation doesn’t seem to be active anymore.
Andrew Chow is working for Blockstream a US based company, that offers a Bitcoin Sidechain solution (Lightning Network) with the focus on privacy and speed. You might find it interesting he broadcasts his code reviews and changes on Twitch.
Marco Falke is a german based bitcoin maintainer starting with 2016.
Chinese miners are providing more than half the global bitcoin hash rate making this a concern for privacy. According to btc.com F2Pool and Bitmain (AntPool and BTC.com) control more than 52% of the hash rate. F2Pool is the first mining pool in China. Bitmain with its headquarters in Beijing China started with mining hardware but is now known as a mining pool company.