How to Sign an Unsigned Base64 PSBT (Taproot Wallet)?

I am encountering an issue while attempting to purchase an Ordinal NFT on Magic Eden using a Taproot wallet. Their API provides an `unsignedBuyingPSBTBase64` string, representing a Partially Signed Bitcoin Transaction (PSBT) encoded in Base64. An example of this string is: `cHNidP8BAPw…….AAAAAAAAAAAAAA=`.

As it stands, this PSBT requires the necessary signatures from my Taproot wallet to become a fully valid transaction. My understanding is that I need to:

1. Decode the Base64 string into a usable PSBT format.
2. Use the private key from my Taproot wallet to sign the relevant inputs of the PSBT.
3. Extract the final, signed transaction (raw transaction or `tx`) from the signed PSBT.
4. Broadcast this raw transaction to the Bitcoin network to finalize the purchase.

My goal is to automate this process via scripting. I am seeking guidance on how to perform these steps using either nodejs or Python. Specifically, I would be interested in:

* Recommended libraries or packages for handling PSBTs in my chosen language.
* The correct methodology for signing the PSBT inputs using private keys derived from a Taproot wallet.
* Any caveats or common pitfalls to avoid when working with PSBTs, especially related to taproot transactions.

I would greatly appreciate any insights, code examples, or references that could help me successfully complete this transaction.