@Eladio P. I've done basically both of the scenarios you described. Granted it was a few years ago (2016, 2017) and some would make the argument that the market is different now but I would disagree. In today's market as everyone continues to say, off market deals are likely you best option but I still see some stuff hit the MLS that could have some potential if you are creative.
The first property I did a FHA loan and did the renovation on the cheap by doing all the work myself and after a year it refi'd for 75% LTV. The key to doing this is finding a property that is cosmetically in the worst condition. You can't have any major issues or it won't qualify for FHA but the cosmetic updates can really sway the appraisal in the end. Even in the end if you have to front some cash to push it past the 75% LTV, it would be worth it to be able to get another FHA loan.
For the 203k to work you really need to find the worst of the worst properties in a good area. I was able to pick up one on the East Side for real cheap and put a ton of work into it to get it past the LTV requirement for a refi. If you are not familiar with big rehabs I would caution you some because you are going to have to deal with properties that have many different issues and some can become bigger issues.
The 203k process can be pretty long and drawn out because the contractor usually knows he has 6 months to get the job done and there's little incentive to get it done quicker. On the front end you really have to have your ducks in a row and expect it will take more than the typical 45 days to close. This may be an issue for some sellers who are looking to get the property sold quickly so be prepared to deal with that.
My advice would be to find a solid first deal and focus on that 100% initially. It's good to have the long term goal in mind but if this is your first rehab project you are going to be plenty busy trying to figure out the first to be focusing on how to get the second. Hard money is an option but that comes with lots of added risk.
Feel free to PM me if you have any specific questions.