@DreymaR's Czech variant of Colemak[eD] is probably the most reasonable go-to choice for many Czechs who transitioned to colemak from the Czech QWERTZ keyboard. However, I am a programmer who stopped using the Czech QWERTZ layout a long time ago and adopted the regular Colemak-DH (ISO) for programming and as a daily driver. The rare cases where I needed to write a sentence or two in Czech, I wrote it with the dead keys and AltGr layers it provides. It was more or less like what @davkol designed.

Now I have the need to write a lot of Czech texts. While I appreciate the accessibility of the Czech letters in the Czech Colemak[eD], I do not want to rewire my muscle memory for all the frequent special characters, so I designed my own layout, taking a more radical approach which puts the Czech language's needs first. It demotes all the numbers, Q, W, X, and F to layer 3 to better accommodate the Czech characters while preserving the frequent special characters.

This is not yet mature and I am testing it and reflecting on the trade-offs I made. It may or may not not be worth it, but without trying this I could not tell. So, here it is.