This was talked about here in early 2019 and I’m sure those who are into disassembly/debugging are already aware of it, but I ran across the NSA’s Ghidra recently and it looks competitive to IDA Pro.
Binaries for Linux and Windows here (requires Java/OpenJDK 11): https://ghidra-sre.org/ghidra_9.2.2_PUBLIC_20201229.zip
It’s a tool the NSA has been using, the disassembler is now open-source, the source code available here: