It looks like their choices are between Sovos and Thomson Reuters only, unless the IRS approves more providers for TY2023, the list of which has not been released yet: https://www.irs.gov/e-file-providers/1042-modernized-e-file-mef-providers

Tax1099.com didn't make the cut for TY2022.  Even if they do get approved for TY2023, I'd suggest sticking with the more experienced, established providers.

Hope this helps.