sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
Purchase a Thunderbolt 3 or 4 NVMe SSD enclosure and populate it with a reputable NVMe drive (Samsung 970/980/990 series are reliable). This combination offers the closest experience to an internal drive and minimizes the frustration of slow load times.
Avoid high Apple upgrade prices for internal storage.
A critical detail often missed in reviews is the SATA controller.