Hey Thomas!
Thank you for your suggestions!
I have already emailed IT House, and I will email Netguru as well.
I will looking into UpWork, but it’s not as easy to work with because UpWork doesn’t want (usually allow) back-and-forth communication between people before the project requester (me in this case) creates the project and (I think, as also with Toptal) pays an upfront escrow fee to UpWork (sidenote: with Toptal it’s a $5000 upfront deposit). This means with UpWork I can only ask a person to give me their past Sharetribe client/references’ phone numbers and email addresses after I have created the project on UpWork.