Thanks to @emoga for mentioning this in Discord.
There is a native version of BoincTasks Js (java script?) for debian linux which works quite nicely on my main computer which is running linux mint 20.3.
https://efmer.com/boinctasks-js/boinctasks-js-download/
I downloaded version 1.27 and to install:
sudo dpkg -i ./boinctasks-js_1.2.7_amd64.deb
To run it from the command line:
boinctasks-js