I've been trying out Beekeeper Studio [https://www.beekeeperstudio.io/] recently, and like that it supports both MySQL and PostgreSQL (and others I don't use). The interface takes a little bit to get used to, but it's been pretty powerful for me.
Before that, or when I'm in a rush to just get something done as I adjust to Beekeeper, I use Postbird (an Electron app) [https://github.com/Paxa/postbird]
Beekeeper Studio maintainer here. It's 100% FOSS and cross platform (Windows, MacOS, Linux).
I love Postgres and started Beekeeper because I wanted 'Sequel Pro for PSQL on Linux'. We have a lot of users so seems like we're doing something right.
Thank you for your work on it! I used Sequel Pro for a long time for MySQL databases and occasionally use its successor Sequel Ace as well, but I'm moving my workflow to Beekeeper Studio as much as I can.
Before that, or when I'm in a rush to just get something done as I adjust to Beekeeper, I use Postbird (an Electron app) [https://github.com/Paxa/postbird]