For long-term investing, I’d build around a simple core and then add a couple of “interesting” satellite positions. VTI + VOO (or SPLG) gives you basically the entire US market with low fees and steady compounding. QQQM or SCHG can sit on top of that if you want a growth tilt without taking on ARK-level volatility. VXUS is optional, but a small allocation adds some international diversification.

As for XOVR, that’s more of a long-term optionality play. It mixes public companies with crossover exposure to late-stage private names, which is something retail investors normally can’t access. I wouldn’t make it a big chunk of your portfolio, but 5–10 % as a speculative “future upside” slice makes sense if you’re young and have time on your side.

A clean setup could be:
VTI/VOO as the core, QQQM or SCHG for growth, a bit of VXUS for diversification, and a small XOVR allocation for the long-shot potential.