I downloaded Ubuntu 18.04.3 LTS and put it on a USB flash drive. Rebooted the MacBook into recovery mode (Command+R) and enabled booting of external media and unsigned operating systems. Rebooted again holding Option and selected to boot from my USB drive ("EFI Boot" in the boot menu).
The Ubuntu boot menu (GNU GRUB version 2.02) shows up, but no matter what I choose in the menu, it just goes into a kernel panic with a lot of ACPI related errors, including this one:
ERROR: Unable to locate IOAPIC for GSI 34
MacBook Pro (13-inch, 2019, Two Thunderbolt 3 ports)
- Processor: 1.4 GHz Quad-Core Intel Core i5
- Memory: 16 GB 2133 MHz LPDDR3
- Graphics: Intel Iris Plus Graphics 645 1536 MB
- macOS Catalina (version 10.15.1)