Likely shipping w/o the proper documentation to enable nextpnr and similar tools, as it's tradition in altera.
I will always choose the vendors that do things properly, when they're even an option.
Like which ones? Honest question.
There aren't any open commercial FPGAs as far as I know. Some have had their bitstream formats reverse engineered though.
We're starting to see open source FPGAs but they are miniscule: https://tinytapeout.com/chips/ttihp26a/tt_um_fabulous_ihp_26...
I think Efinix did something internally, with Yosys.
Not many options unfortunately. Today that's GateMate.
Next best thing? The mature reverse-engineered families nextpnr[0] supports.
0. https://github.com/YosysHQ/nextpnrhttps://github.com/YosysHQ...
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