Is there any way to use a Solana wallet keypair and load it into the JWKInterface as per the node_modules/arweave/node/lib/wallet.d.ts and then create an Arweave TX with await arweave.createTransaction({ data }, jwk);?
Given metaplex uses an API call for their Arweave uploader and it's a hidden piece of code would be nice to crack this in native JS/TS if it's possible.
Are you referring to https://github.com/ArweaveTeam/arweave-js ?
That requires a arweave and not a solana wallet. You can use e.g. arkb for the upload
If you want to build something yourself in JS have a look at the cookbook. https://solanacookbook.com/references/nfts.html#upload-to-arweave