Late to the party, but congrats on picking Fedora and Ubuntu — both are solid choices on a T480. One practical tip from experience: update the BIOS and Thunderbolt firmware first via fwupd (sudo fwupdmgr get-updates) — Lenovo ships firmware to LVFS, and the T480's early Thunderbolt issues were fixed in later firmware versions. If your T480 has the Nvidia MX150 variant, you'll want the proprietary driver: akmod-nvidia from RPM Fusion on Fedora, or Ubuntu's Additional Drivers tool. Also worth installing TLP for the dual-battery setup so you can set charge thresholds on both batteries — that matters a lot for a used machine's battery health.