user47827: Apparently (credit 0xB10C) there are only 20 key-path and 5 script-path spends of P2TR outputs on the Signet blockchain today (July 7th 2021). How can I increase this number today with say the Bitcoin Core wallet in the upcoming 22.0 release? If there are multiple ways (of varying levels of complexity) please outline them all.

user47827: This is a draft answer (incomplete).
To get set up on Signet ie sync the Signet chain and claim some Signet Bitcoin, follow these instructions. (You can run a Signet node in parallel with your mainnet node, ie same hardware)
You now have funds at a non-P2TR (i.e. SegWit v0, bech32) Signet address. Now you need to generate a P2TR address to send funds to so you have funds at a P2TR address (so you can spend from it).
You can't generate a P2TR (SegWit v1, bech32m) address in the wallet using getnewaddress:
./bitcoin-cli -signet -rpcwallet=insert_wallet_name getnewaddress "" "bech32m"

returns
error code: -12
error message:
Error: No bech32m addresses available.

So you need to construct a Taproot descriptor manually and then import it into your descriptor wallet.
An example Taproot descriptor is:
tr(c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5,{pk(fff97bd5755eeea420453a14355235d382f6472f8568a18b2f057a1460297556),pk(e493dbf1c10d80f3581e4904930b1404cc6c13900ee0758474fa94abe8c4cd13)}) 

which describes a P2TR output with the c6... x-only pubkey as internal key and two script paths.
If you only want to do a key path spend you only need the equivalent of:
tr(c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5)

You can import a tr(xprv/insert_xpriv_here) descriptor so that your descriptor wallet has the private key to spend from it.
To do: Send signet Bitcoin to this descriptor wallet, spend back to a SegWit v0 address (sendtoaddress) Include generation of xprv?
TBC
This was also discussed on the bitcoin-dev mailing list.

47827: <p>Apparently (credit <a href="https://x0f.org/@0xb10c/106538694483691589" rel="nofollow noreferrer">0xB10C</a>) there are only 20 key-path and 5 script-path spends of P2TR outputs on the Signet blockchain today (July 7th 2021). How can I increase this number today with say the Bitcoin Core wallet in the upcoming 22.0 release? If there are multiple ways (of varying levels of complexity) please outline them all.</p>
 47827: <p>This is a draft answer (incomplete).</p>
<p>To get set up on Signet ie sync the Signet chain and claim some Signet Bitcoin, follow <a href="https://bitcoin.stackexchange.com/questions/98553/how-do-i-get-set-up-on-signet">these instructions</a>. (You can run a Signet node in parallel with your mainnet node, ie same hardware)</p>
<p>You now have funds at a non-P2TR (i.e. SegWit v0, bech32) Signet address. Now you need to generate a P2TR address to send funds to so you have funds at a P2TR address (so you can spend from it).</p>
<p>You can't generate a P2TR (SegWit v1, bech32m) address in the wallet using <code>getnewaddress</code>:</p>
<pre><code>./bitcoin-cli -signet -rpcwallet=insert_wallet_name getnewaddress &quot;&quot; &quot;bech32m&quot;
</code></pre>
<p>returns</p>
<pre><code>error code: -12
error message:
Error: No bech32m addresses available.
</code></pre>
<p>So you need to construct a Taproot descriptor manually and then import it into your descriptor wallet.</p>
<p>An <a href="https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md" rel="nofollow noreferrer">example</a> Taproot descriptor is:</p>
<pre><code>tr(c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5,{pk(fff97bd5755eeea420453a14355235d382f6472f8568a18b2f057a1460297556),pk(e493dbf1c10d80f3581e4904930b1404cc6c13900ee0758474fa94abe8c4cd13)}) 
</code></pre>
<p>which describes a P2TR output with the <code>c6...</code> x-only pubkey as internal key and two script paths.</p>
<p>If you only want to do a key path spend you only need the equivalent of:</p>
<pre><code>tr(c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5)
</code></pre>
<p>You can import a <code>tr(xprv/insert_xpriv_here)</code> descriptor so that your descriptor wallet has the private key to spend from it.</p>
<p>To do: Send signet Bitcoin to this descriptor wallet, spend back to a SegWit v0 address (sendtoaddress) Include generation of xprv?</p>
<p>TBC</p>
<p>This was also <a href="https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2021-October/019533.html" rel="nofollow noreferrer">discussed</a> on the bitcoin-dev mailing list.</p>
