xxAnonymousXX According to mcstacker.net, it's:

/give @s command_block[block_entity_data={id:"command_block",Command:"/tellraw @p test"}]

Tried this in a 1.21.8 singleplayer world. Seems to work fine.

Now, converting the /give command to Wurst commands, you need to first use .give and then .modfiy, because .give itself doesn't handle item components yet:

.give command_block
.modify set block_entity_data {id:"command_block",Command:"/tellraw @p test"}

And when trying this in my 1.21.8 world, I seem to get the exact same command block as the /give version.

For the minecart and spawn egg, the approach would be similar. You'll just need to figure out the correct /give syntax first.

Unfortunately ChatGPT often suggests the old pre-1.20.5 syntax, which doesn't work anymore in 1.21.8. Command generator websites like mcstacker.net and gamergeeks.net should be more reliable for now, at least until the GPTs get more familiar with Minecraft's item component system.

However, once you have a working /give command, ChatGPT should be able to convert it to .give / .modify syntax for you as long as it's given an example. Here is a basic prompt template that you can use:

<vanilla_example>
/give @s command_block[block_entity_data={id:"command_block",Command:"/tellraw @p test"}]
</vanilla_example>

<wurst_example>
.give command_block
.modify set block_entity_data {id:"command_block",Command:"/tellraw @p test"}
</wurst_example>

given the above example, convert the following vanilla /give command to wurst syntax:
[insert your /give command here]

Hope this helps!