Author here: I actually used a thunderbolt nvme and adapter for a bit. Then, for kicks I got another one and combined them in a raid-0 on macos. Realizing I didn’t want to run nvme’s, in raid-0 over two cables in any sort of production (homelab - I use production loosely here), is what sent me down the Thunderbolt rabbit hole that precipitated this blog post.

In case a single-cable solution would work, I've been using an external TB NVMe RAID 0 in this enclosure for several months and it's worked flawlessly: https://www.amazon.com/gp/product/B08S5JPWR6 (The only drawback is that the power supply is bizarrely-large, and the power connector feels a bit janky. In practice it hasn't been an issue.)

Not the op, but if the nas was pre-existing, and already serving other network clients, no reason to add a second one.

Not OP, but my files are shared with many hosts. Having local files are a PITA to manage coherent state.