Markdown Editor

I have just started using a markdown editor, which is very popular these days. In the old days, I used to write directly html tags and such in an editor (:-u), but that is not very efficient these days, so I think markdown editors are very good tools that allow various modifications to be made with text.
Recently, so-called integrated environments for coding, not just markdown, seem to be very popular. Some of them can do various things, not only check the syntax of a programming language, but also compile, run, and debug it. This may be due in part to the increase in the number of people coding with the spread of python. Many people, especially science students, may have used python at least once. I think markdown is also ideal for writing papers that include mathematical formulas.
I have also tried several tools such as Boostnote / Atom / VS-Code / Inkdrop, and tried programming Sikulix, an RPA tool, and writing this blog, each full of great features and very interesting, but in the end I reverted to vi for coding (lol). I guess it's hard to change the habits you acquired in the past, and there is still nothing that can beat the ease of operation of moving the cursor without taking your hands off the keyboard (without a mouse), or the regular expression + line search and replace (just my personal opinion, lol).
I went back to vi for coding, but for blogs and memos, I want to use a markdown editor because I use Japanese , two bytes charactors, and I don't want to use the Japanese input in vi because the ESC and Kanji keys are so close together that I often press the wrong keys. So, let me summarize my requirements for a markdown editor

• Convert to html
• Can be used and shared on multiple devices
• Free of charge (lol)

There are some blogs these days that can upload markdown as-is, but I may switch to a new one in the future, so html uploads are more stable. If possible, it would save me time if I could copy it to the clipboard instead of outputting it to a file.
Also, since I want to write blogs whenever I have an idea, I would like something that can be used on PCs (Linux/Windows), tablets, and smartphones (iOS/Android) and that allows me to share what I have written.
I would be happy to pay for a tool if I really need it, but since I have gone back to using vi for programming, I don't need complicated functions, so I think a free tool would be sufficient.
I started with StackEdit, which meets these requirements, and it is quite good: it can be easily shared using Google Drive, and since it is http-based, there are almost no restrictions on devices or operating systems. Best of all, the html output can be easily exported to the clipboard. However, for some reason, I can't copy and paste on iOS, which I think is the case at this point. For some reason nothing is in the clipboard when I copy. It is possible that my settings are bad, but not being able to copy and paste is fatal for an editing tool.
After that, I tried Joplin and have been using it up to now. html conversion is a little disappointing that it only outputs files and not copy to clipboard, but other than that it is very comfortable. Even I may switch to another app soon. (LOL.