Out of curiosity, how - by your preference - should this be done so that it's easier for the user?
something like:
curl -fsSL https://repo.aosc.io/pubkeys/repo/oma.gpg | sudo gpg --dearmor -o /usr/share/keyrings/oma.gpg
echo "deb [signed-by=/usr/share/keyrings/oma.gpg] https://repo.aosc.io/oma $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/oma.list > /dev/null
sudo apt update && sudo apt install -y oma
Microsoft also has a "download deb and install", which I still consider slightly better than curl | bash; it's basically the windows install flow. People who are using a GUI can just double click it, people who want to see what it's going to do can examine it, and your (unsafe) one-liner is `curl XXX.deb && dpkg -i XXX.deb`. Plus it can be shipped to a multiple machines at once easily.
And hey, you already know they have dpkg.
(edited: mangled my command spacing a bit)