The first pool to signal for taproot was slush. Slush is Bitcoin's oldest standing mining pool by a wide margin.

As achow notes, I haven't had much to do with taproot-- I think the extent was that I peer reviewed some of the proposal on a couple occasions, and spent some time in public forums explaining it to people (and kicked off the initial idea, of course, over three years ago).  As a bitcoin user and investor whos interested in privacy I'm excited about it, however.

Taproot wasn't invented until after I had no further relationship with Blockstream, I haven't worked with blockstream since Dec 2017. Achow's statement that it in any way originated at blockstream is mistaken, I assume he's confused about the timeline since taproot was a bit after I left (and IIRC achow101 wasn't employed there at the time, he'd previously been an intern, but I believe he wasn't at the time).

I don't have any commercial relationship with anyone regarding Bitcoin other than being a customer of exchanges (also wouldn't be relevant if I did since I haven't been involved in taproot's deployment or in it's development for years).  I consider DCG an adversary and certainly do not have any relationship with them.  I don't believe I'd ever heard of foundry USA prior to seeing it on taprootactivation.com/taproot.watch.

There is plenty of information about taproot available online, going back years, including in less specialized publications:

Taproot Is Coming: What It Is, and How It Will Benefit Bitcoin (January 24th 2019)

Taproot at MIT Bitcoin Expo (April 6th 2020)

Bitcoin’s Future: Exactly How a Coming Upgrade Could Improve Privacy and Scaling (April 7th 2020)

Taproot and Schnorr: The Biggest BTC Upgrade for 2021 (February 6th 2021)

... just to cite a few general audience examples.

Plus lots of other coverage in more specialist publications, e.g.:

2018

• Taproot (major developments of 2018, January)
• What a taproot soft fork might look like

2019

• 2019 year-in-review: taproot
• Impact of bech32 length-change mutablity on v1 segwit script length
• Blog post about x-only schnorr pubkeys
• Bitcoin Optech schnorr/taproot workshop
• Announcement of structured taproot review
• Update on changes to schnorr, taproot, and tapscript
• Suggested removal of P2SH address wrapper from taproot proposal
• Executive briefing: the next soft fork
• Reducing taproot commitment size
• Overview of Taproot and Tapscript
• Extended summary of bip-taproot and bip-tapscript

2020

• 2020 year in review: Taproot, tapscript, and schnorr signatures
• Website tracking miner support for taproot before signaling begins
• Summary of results from surveying developers about taproot activation
• Bitcoin Core #19953 merged with consensus implementation of BIP341
• Discussion about taproot activation parameters
• Discussion of various topics, including taproot activation
• Upgrading LN commitment formats, including for taproot
• Question about the different features in taproot for upgrading
• Question about leaf versions in taproot
• Discussion about backporting wtxid relay for taproot activation
• New chatroom for discussing taproot activation
• Coinpool: using taproot to help create payment pools
• Taproot eliminates vulnerability related to segwit fee overpayment attack
• BIP341 transaction digest amended with extra commitment to scriptPubKeys
• Example sizes of multisig taproot transactions
• Request for comments on amending BIP341 taproot transaction digest
• Request for additional signature commitment to previous scriptPubKeys
• Security analysis: taproot in the generic group model
• Taproot security from quantum computing threats
• Discussion about taproot versus alternatives
• btcdeb adds <code class="highlighter-rouge"]tap</code> command for experimenting with taproot and tapscript
• Final organized review, presentation slides, and LN integration ideas

2021

• Rust Bitcoin #589 starts implementing support for taproot and schnorr sigs
• Miners encouraged to start signaling readiness for taproot
• Bitcoin Core 0.21.1 released ready to activate taproot
• BIPs #1104 adds activation parameters to the BIP341 taproot specification
• Bitcoin Core #21377 and #21686 add taproot activation mechanism and params
• Compromise proposed to use MTP to activate taproot with speedy trial
• Regular meetings scheduled to help activate taproot
• Discussion of quantum computer attacks on taproot
• Documenting the intention to use and build upon taproot
• Alternative methods of activating taproot discussed
• Summary of taproot activation discussion regarding BIP8 <code class="highlighter-rouge"]LOT</code> parameter
• Summary of taproot activation discussion &amp; additional meeting scheduled
• Meeting to discuss taproot activation mechanisms

not to mention the list discussions, public meetings, review club, specifications, and pull requests...

But fortunately, even if someone managed to live under a rock and miss all that--  if they don't like taproot, for whatever (probably confused) reason, they don't have to use it.  How someone chooses to manage their own Bitcoin should be no ones business but their own.