Doing simultaneous things in a bash script?

I am trying to run this bash script:

source ~/miniconda3/etc/profile.d/conda.sh
gnome-terminal --tab -e "conda activate env_num_1 && jupyter lab"
conda activate env_num_2
cd some_path 
gnome-terminal --tab -e "sleep 5 && firefox myurl" #
bash "command that starts web server" #It takes a few moment to boot up hence the sleep function

For whatever reason gnome-terminal are opening the tabs but neither are executing the commands it has been given. What can I do to fix this?

EDIT: Tried suggestion below (gnome-terminal --tab -- sleep 5 && firefox myurl) in just the terminal, I get

Failed to execute child process “conda activate machine-learning-env & jupyter lab”: Failed to execve: No such file or directory

EDIT 2: Kept on fiddling with it, this gives roughly what I want.

#!/bin/bash
source ~/miniconda3/etc/profile.d/conda.sh

conda activate env1 && jupyter lab &
(conda activate env2
cd mydir
bash webui.sh & (sleep 10 && firefox myurl))

but it seems to do everything in one terminal. I would like to close one program and keep the other at my discretion.But I guess there must be another way?

I understand, your want to do something like that:

gnome-terminal --tab -- sh -c "conda activate env_num_1 && jupyter lab"

@see warning in man gnome-terminal for --command, -e=COMMAND option

Add a read command for debugging:

gnome-terminal --tab -- sh -c "conda activate env_num_1 && jupyter lab; read -p \"press enter key\""