I’m going to try to address this in the nicest way.
If you can swing it, get yourself a power meter for outside and to use with powermatch. Many trainers are known to not quite be as precise as they should be.
Once you start collecting data and learn how the different zones and tss levels feel, it becomes much easier to “estimate” your tss from rides where you may not have a pm. HRtss is nice, but nothing trumps feel and RPE. If I go for a ride on my mtb or cx bike I do not have a power meter and will only sometimes wear a hrm. I can usually estimate my TSS within 5-10 of the hrTSS value given by training peaks because I just have this experience built up.
Get the power meter. It’s literally the best tool you can use to start accumulating the knowledge you need to train your body in the proper way.