I've deleted my posts and comments using a userscript to overwrite them prior to deletion. I haven't deleted the account yet however as I don't think private subs let you delete your comments. If you want recommendations for this Power Delete Suite is the easiest to use but may stop working with the API changes from what I've heard. Better Reddit Delete is one of many userscripts to delete your history. You will need a user script manager such as Greasemonkey for Firefox

Long term I plan to move some of my subs to RSS feeds from Teddit. I will likely also have Libreddit as a PWA on my phone with all of my existing communities added.

For the small amount of communities I interact with that I don't see moving to the Fediverse I'll access them through Old Reddit only. I'll likely make multiple accounts to separate interests and delete them / make new ones after a certain amount of time.