Chrome: https://chrome.google.com/webstore/detail/pockettube-youtube-subscr/kdmnjgijlmjgmimahnillepgcgeemffb
FireFox: https://addons.mozilla.org/en-US/firefox/addon/youtube-subscription-groups/
Safari: https://apps.apple.com/us/app/id1533703891
Edge: https://microsoftedge.microsoft.com/addons/detail/pockettube-youtube-subsc/klfeohnijmogpjoeenglhonjfiacajpp
Opera: https://addons.opera.com/en/extensions/details/pockettube-youtube-subscription-manager/
Android: https://play.google.com/store/apps/details?id=com.youtubesubscriptionmanager
iOS: https://apps.apple.com/us/app/pockettube-for-youtube/id1475688814
Tutorial ...
https://www.youtube.com/watch?v=rylGj42u034
https://ourtechroom.com/fix/manage-youtube-channel-subscriptions-into-group-folder/
PS. just in case you're looking for a kinda related AutoHotkey driven solution @TheDewd is offering it
here 