During the COVID-19 closure, I'm still doing weekly questions to make sure students are getting a little practice speaking. I could use FlipGrid for this, but one thing I've learned in teaching with technology is that simpler is better than more complex, and every time we introduce a new tech tool into the classroom, it adds a layer of complexity. When I was on a tech committee, one of the tech people at my university reminded us that even if we're only asking students to learn 2-3 new tools, if every teacher is asking students to learn 2-3 new tools that are different, that adds a lot of extra work to their load. Since we're already using Google Classroom and Google Classroom allows students to upload video files, I've just been using that for the weekly question. The upside is that they're already used to submitting assignments via Google Classroom, so there's little to no learning curve. The downside is that Google Classroom doesn't currently have an efficient way to leave audio or video feedback. (You could make a video and post a link in a comment, but multiply that by 100 and you can kiss doing anything else goodbye.)
I can give feedback on comprehensibility, sentence structure, and vocabulary choice using the comment feature, but giving feedback on pronunciation without using audio or video files is harder (and this is where FlipGrid may yet convince me to use it, since this feature is already integrated). But for now, when I notice a pronunciation issue, I put Google Translate and Word Reference to good use. Both websites include the option to play audio of whatever word you put in. So I send a link for the word or words that students are having trouble with, and then they can listen to the Google Translate or Word Reference pronunciation. I prefer Word Reference because it appears to be a real human voice rather than a robot voice, and it also has options for a few different dialects of Spanish. But either one will give students the main idea of how a word is pronounced.