Read some of the current posts, there are several folk, boys and girls, starting their adventures in running with a THR at the moment, lots of info to absorb.
In my case, I was jogging at 6 weeks and back in the mountains at 4 months, but this was over 4 years ago so no Covid to recover from..
I started on hard flat surfaces, in ordinary trainers, at a very slow jog/walk/jog, checking for new pains/funny feelings and being very careful. The hospital physio, however, stuck me on a treadmill and made me run properly (but not very elegantly) so I stopped worrying and so my 6 week jog was actually at parkrun, 5k. I went down the route of small steps, faster cadence in flat shoes – some go the other way and get Hoka or similar soft cushioned shoes, and start running on grass. I was fit before the op. so was reasonably quick quite quickly, this did not last very long and had to build up mileage slowly to regain proper fitness. Basically my best advice is to ‘suck it and see’ – I recorded my progress on my Garmin devices, nice to be able to look back and see how far you have come.