https://discourse.ubuntubudgie.org/t/appindicator-applet-wont-scale-icons-on-top-panel/2062
https://discourse.ubuntubudgie.org/t/app-indicator-and-panel-size/3120
you will have to roll up your sleeves and DIY but it sounds like itcan be done. read the article. if you can find the right file to edit you may be in business. unsure Solus Budgie and Ubu Budgie would give the .rss the same name