AFAIK - Alchemy Installer - It is currently not supported in tridion sites 9.0+.
Anwer to your question
Q: Is there any way to install the Alchemy plugin without Alchemy?
A: No, Alchemy plugins wont work without Alchemy framework.
There is a possible hacky way to install Alchemy Installer in Sites 9.0 and 9.1 by your own risk.
The current Alchemy Installer checks the Tridion version to 8.5, If you change the the below registry path key name "Version" value to "8.5" and then try to Install the Alchemy (Alchemy4Tridion-v18.104.22.168.msi), once completed then DO NOT FORGET TO REVERT version key name value back to as orginal value (please note down or backup the registery before change).
After that you should be able to install the 8.5 plugins in sites 9.0 or sites 9.1, most of the 8.5 coreservices plugins are backward compatible in Sites 9.0 and 9.1, I can confirm "Export Item List" plugin works in sites 9.1.
I hope it helps.