None of those by default, Pulsar tends to stick to being an editor with as much as you need but not more by default. However one good thing about forking Atom was that we kept all the packages that were published to atom.io (more than 10k of them). You can browse them the PPR (Pulsar Package Registry) which was reverse engineered from Atom's closed source backend from scratch before they took down the site - https://web.pulsar-edit.dev/.
I won't say I guarantee all of these will work but our Discord channel in particular is rather active so people more knowledgeable than I might well be able to help out, its a friendly place. We have other social channels as well should you prefer them.
A bit of gratuitous self promotion but just to let people know if you liked Atom and are still using it or maybe you migrated to a new editor and still miss Atom, it was forked as Pulsar which is entirely community-led and is seeing a lot of active development to bring it up to date. We also have a lemmy community at !pulsaredit@lemmy.ml
This is the problem, making the fork known to the userbase of the original software. When the Atom text editor was killed by Microsoft we decided to fork it as Pulsar but it was an uphill struggle to really get the word out. We got a massive boost when the youtuber Distrotube featured us in an episode and again with an itsfoss article but we still routinely find people who have been using Atom without knowing we even exist.
Its the same as the GitHub problem though, if you want to get community involvement then the necessary evil is to go where the people are. We use GitHub and Discord as that is where the vast majority of our users are, our Lemmy community sees barely any activity over our subreddit, we have barely anyone clamouring for Matrix or IRC. Our Mastodon is probably our only large 'fedi or fedi—adjacent' platform and thats because we drew the line at twitter. Would I love to get away from Discord? Absolutely, but that limits our ability to have an active community whilst we are still growing the project.
I know it doesn't tick the boxes but there technicality is a Microsoft made, open source, alternative to Explorer. The original File Manager for Windows 3.1 and it is still seeing active development. Just thought to bring it to attention for a bit of nostalgic fun but I actually find myself using it a fair bit.
You are probably already aware but there is OpenSCAD which allows you to model via programming rather than by UI. Not really an apples to apples equivalent but I find it decently interesting. I do wish there was something a little more more overtly friendly to beginners like Fusion360 though.
I can't say I really use any of the older style BBS ones like phpBB but there are plenty of smaller software communities using Discourse based forums. For less active communities they are far superior to Discord due to the more asynchronous nature and gives you a lot more control than Reddit/Lemmy.
Somewhat self promoting for the first two of these items as I'm directly involved. Leaving out the more obvious ones (Linux distro etc.) as they will have been mentioned. I'll stick to some of the less known things I use.
Really like tuta, have to admit that i've not looked closely at the paid options but they provide their services for free to our open source project and it functionality even on that tier is pretty great.
For a file manager (GUI) I rather like PCManFM, particularly on tiling WMs. I've been wanting to try out Xplorer but not got around to it, last time I tried the appimage was a bit broken.
Video editors I've only used, but rather like, Kdenlive.
I got to that once, on mobile I've never worked out the rule for when FF opens a new tab vs opening a site in your current tab. They just kind of silently accumulate.
Kitty the vast majority of the time but slowly using Ghostty more and more as it improves. Sometimes use Tabby and have been looking into Wave recently. I also use the x-terminal-reloaded package in the Pulsar editor for a dock terminal if im doing something in it at the same time.
None of those by default, Pulsar tends to stick to being an editor with as much as you need but not more by default. However one good thing about forking Atom was that we kept all the packages that were published to atom.io (more than 10k of them). You can browse them the PPR (Pulsar Package Registry) which was reverse engineered from Atom's closed source backend from scratch before they took down the site - https://web.pulsar-edit.dev/.
Specifically there are a bunch of remote edit packages that work over SSH, a ton of Docker packages and there are plenty of debugging packages both generic and language specific and there are indeed test runner packages.
I won't say I guarantee all of these will work but our Discord channel in particular is rather active so people more knowledgeable than I might well be able to help out, its a friendly place. We have other social channels as well should you prefer them.