if you will delegate to an instance the decision on what to show you on your browser when you connect to it, you'd have to pick an instance that does that for you. mastodon mainline could make that configurable. someone could patch mastodon in their instance to behave as you wish. you could run your own instance. you could run something other than mastodon that behaved as you wish. these are all in line with the notion of decentralization and browser-based UX. I sense there's some other unstated requirement.