Thanks for your questions. First, I would say it is way too early for any kind of vows, private or otherwise. I appreciate you are living a period of solitude right now, but it is not eremitical, not yet anyway. Remember, you have retired and are in a transitional period of greater solitude. This is not eremitical solitude; eremitical solitude is not transitional solitude. You are beginning to negotiate how you will live retired life with all the questions that raises about how and why you are going to live moving forward in whatever way you choose to do that. Also, we are still dealing with the pandemic's enforced solitude in most places. Neither is this eremitical solitude --- though for some it might grow into this. Give yourself at least a year of living as you are. Also begin working regularly with a spiritual director who can assist you in this transitional time of discernment and bereavement (for there is serious loss upon retirement).
Especially continue to ask yourself why you are doing this. Because there is only ONE reason to be living eremitical solitude, namely, God calls us to do so. So, does God seem to be calling you to this? If so, do you want to truly respond to that call in this way or not? At that point you might write yourself a Rule or set of guidelines regarding how God wants you to live this response of yours. Central to this Rule or set of guidelines will be an account of the ways God works in your life and how you respond to that working. There will be values you want to witness to, practices you want to model. There will be a vision of the life you are choosing to live. A Rule, Plan of Life or set of guidelines should reflect all of these. Live these for another year or two. With the assistance of your director, modify them as needed in the direction of how you feel called by God to live and continue living in this way for another couple of years; if at this point you are still clear that you are called by God to this, then, if you need to do this, write a liveable Rule you propose to live for at least five years.
If, at every point you can affirm not only that you want to be united more closely with Jesus, but can also say, "Jesus, I feel you calling me to unite myself to you in this specific way", a vow is not going to change that in the way you believe (or fear). It should express, codify, and strengthen your commitment of self. It is true that sometimes after making the vow, in the course of years you may feel at times that you are only living this because you committed to doing so. So? What if you were speaking of another relationship, one with a good friend where you committed to always "having their back" or something. Would that promise or commitment vitiate the friendship? Or is it a way of honoring and protecting the friendship in good times and bad? Are you friends merely because you promised you would have this person's back or did you promise what you did because of something deeper and very real? With vocations these same dynamics can be at play and your vow can hold you until you regain a better sense of things -- or as you negotiate seemingly chaotic periods of growth where you move "from faith to (deeper) faith".
What I am saying throughout this is that only over time, with the help of a spiritual director, and lots of prayer, can you come to clarity on whether God is calling you to eremitical life. A commitment should not be made too early, but once it is made, it should help you to continue living a committed life. The commitment, if made rightly and based on good discernment, should strengthen the way you are living and intensify your love for Jesus. If it becomes empty in some way, it obliges you to get back in touch with your original motivations and sense of call. It obliges you to discern afresh and get in touch with what you initially discerned if that is possible. If, after some months of praying and working with your director on this, you cannot do that, then perhaps it is time to leave that commitment and this attempt at being a hermit behind.
I sincerely hope this is helpful. Please get back to me if it raises more questions.