Thanks @Frankc1450@union.place!
In short: using my own #IndieWeb blog and blogging software, which has no length limit.
A bit longer:
I make my posts by writing them in @barebones.com’s excellent BBEdit (@bbedit@mastodon.social) text editor, scp them to my blog, which does all sorts of automatic linking (including #hashtags), embedding, generating of archives, streams, feeds, sequential navigation, etc.
I use #BridgyFed to #federate my posts to #fediverse followers on #Mastodon and other #ActivityPub supporting services. More details on that here: https://tantek.com/2022/301/t1/twittermigration-bridgyfed-mastodon-indieweb