Looks very cool. I started working on my own version of this to self host in my LAN. First issue I ran into was the lack of understanding certain CSV formats. For example, Vanguard is so common that I support their export format exactly. Might be worth thinking about focusing on a few common brokerages (vanguard, fidelity, schwab) and making the experience for those really good. Otherwise it's all too manual and most people won't bother going through the hassle of it all.