A couple of the apps do have this "multi community" feature, if you're a mobile user. Summit definitely does, Raccoon (the one I'm replying from now) technically does but it's pretty broken so I'm hoping that gets looked at soon. And tbh maybe more of them do now, it's been a while since I checked!
You've had some well-meaning but ultimately not quite accurate answers in this thread so just to clarify:
You can follow, post to and interact with Lemmy communities from Mastodon, because they're treated the same way as a "group" on Mastodon in general.
You can NOT follow and interact with Mastodon users from Lemmy, because Mastodon accounts are individual "users" and Lemmy doesn't have the concept of following and interacting with users, only with communities. If Lemmy ever does add a feature to let us follow other users, then in theory following Mastodon users will also become possible.
I've not "used" it but for some reason they've decided to include one of my accounts in their gaming feed so I checked it out.
Just seemed like a too-broad-to-be-useful repost bot, although apparently there are real people "curating" too. Why they'd repost my inane ramblings if it's actually human-curated, I do not know.
I do however know quite a few people who blocked them already since it just looks at first glance like complete spam. Like most Fedi stuff, they could probably do with communicating better what it is they're actually trying to do.
That's my main concern. Seeing content from other platforms in my Mastodon feed is pretty great right now (Lemmy, PeerTube etc). But hashtag feeds could quickly get overrun by something like this if it works the same way.
That said, making this its own thing instead of building a "reels" for Pixelfed suggests the dev already knows separation will be important, so 🤞
Bit of a weird one, I use the default UI myself and haven't had any issues with it. But maybe if you can post a pic it'll help us figure out what's going on?
There are some opt-in directories for finding people by topic.
Such a weird way of framing a cool new feature.
The problem it solves is that typing on a phone is annoying, and that's a problem every other app has too.
The "problem" of people not being able to find you if you give them your handle instead? Based on recent experience of a lot of non-techy friends signing up and finding and following me with literally no problems, I'm pretty sure that isn't a thing.
It's how both platforms (and I assume the rest of fedi) work. If you follow an account from Mastodon, that your server has never seen before, it'll be blank until new posts are made. That goes for other Mastodon accounts, Lemmy communities / users, Pixelfed accounts, PeerTube channels, etc etc.
If you subscribe to a Lemmy community, and your Lemmy server has never seen that community before, same thing. Blank until new posts.
It caused a lot of confusion and tech support last summer but now that most servers know about most other ones I guess it's not as common to run into these days :D
Pixelfed only shows media posts, so if you're following a Mastodon account you will see any posts made with images attached but not text-only ones.
The blank feed is just because nobody from your Mastodon server was following this account yet. Works the same as following any other new-to-your-server Masto account in that respect, but it should start showing new posts made since you followed.
Honestly this was on my mind because I saw a clickbait YT title the other day claiming that the creator had one chance to do a thing or would have to "be a janitor forever" which...a) that's ridiculous and b) doesn't sound half bad to me at all 🤷♀️
Unfortunately that link doesn't help much. Currently among the list of "recommended instances" (followed by a claim that it "doesn't matter" which of these you choose) are a French-speaking instance, a crypto instance, and an anime instance. Hardly welcoming places for your average person, unless you happen to be a French crypto bro looking for porn in which case you are definitely well catered for.
OP might not have all the details worked out but their point is a good one, and it's an issue on Mastodon as well. It's all well and good having a one-liner description about each instance but it can be quite a trawl to find the actual important info you need to make a decision.