Long time user of HeidiSQL here. I respect the author a lot. He's been tirelessly working on this project for many years, mostly alone. Of course, that's due to the closed nature of Delphi.
It's great news that this is now available for Linux, but the better news for me is that I can now build it on Lazarus / FreePascal. Even if it doesn't support all the features (eg MSSQL), at least I can now contribute fixes for some UI issues that have been bothering me.
I can successfully build the FreePascal version on Windows and it runs... fine. Feels a little less snappy than the Delphi version and there are some UI padding issues. But it's a massive step in the right direction.
If you can, please support this project, either financially or through code. contributions. IHMO what is dearly needed is for the different SQL dialects to be abstracted out properly. It's currently done in a bit of a crude way (no disrespect to the author) and it will require a big refactoring to get it right, but will open doors to more dialects.