I've rebuilt almost all my components from old extant source trees with the new SDK for x86 and x64.
They fully support Dark Mode, v2.0 and 64-bit foobar2000 so if you rely on a niche component of mine it shouldn't be blocking any upgrades for you.
The updated components are:
Affix Silence (foo_dsp_silence) (https://www.foobar2000.org/components/view/foo_dsp_silence)
Equalizer split (foo_dsp_eqsplit) (https://www.foobar2000.org/components/view/foo_dsp_eqsplit)
New Named Playlist (foo_new_playlist) (https://www.foobar2000.org/components/view/foo_new_playlist)
Remove Playing Track (foo_np_remove) (https://www.foobar2000.org/components/view/foo_np_remove)
Replaygain Override (foo_rg_trn) (https://www.foobar2000.org/components/view/foo_rg_trn)
Seekbox (foo_seek_box) (https://www.foobar2000.org/components/view/foo_seek_box)
Timebomb (foo_timebomb) (https://www.foobar2000.org/components/view/foo_timebomb)
The sole component _not_ updated is the Waveform Seekbar (foo_wave_seekbar), that one requires quite some overhaul to build on modern toolchains but I think I've got a road forward there eventually with Direct3D 11.0 and shader compatibility mode.